diff --git a/administrator/components/com_scheduler/src/Traits/TaskPluginTrait.php b/administrator/components/com_scheduler/src/Traits/TaskPluginTrait.php
index cebb7b65f992e..16f3ac1481542 100644
--- a/administrator/components/com_scheduler/src/Traits/TaskPluginTrait.php
+++ b/administrator/components/com_scheduler/src/Traits/TaskPluginTrait.php
@@ -215,7 +215,7 @@ protected function getRoutineId(Form $form, $data): string
 		// If we're unable to find a routineId, it might be in the form input.
 		if (empty($routineId))
 		{
-			$app       = $this->app ?? Factory::getApplication();
+			$app       = $this->getApplication() ?? ($this->app ?? Factory::getApplication());
 			$form      = $app->getInput()->get('jform', []);
 			$routineId = ArrayHelper::getValue($form, 'type', '', 'STRING');
 		}
@@ -248,7 +248,7 @@ protected function logTask(string $message, string $priority = 'info'): void
 
 		if (!$langLoaded)
 		{
-			$app = $this->app ?? Factory::getApplication();
+			$app = $this->getApplication() ?? ($this->app ?? Factory::getApplication());
 			$app->getLanguage()->load('com_scheduler', JPATH_ADMINISTRATOR);
 			$langLoaded = true;
 		}
diff --git a/libraries/src/Plugin/CMSPlugin.php b/libraries/src/Plugin/CMSPlugin.php
index c639b1440402f..2a544990c6cdd 100644
--- a/libraries/src/Plugin/CMSPlugin.php
+++ b/libraries/src/Plugin/CMSPlugin.php
@@ -10,6 +10,7 @@
 
 \defined('JPATH_PLATFORM') or die;
 
+use Joomla\CMS\Application\CMSApplicationInterface;
 use Joomla\CMS\Extension\PluginInterface;
 use Joomla\CMS\Factory;
 use Joomla\Event\AbstractEvent;
@@ -75,6 +76,15 @@ abstract class CMSPlugin implements DispatcherAwareInterface, PluginInterface
 	 */
 	protected $allowLegacyListeners = true;
 
+	/**
+	 * The application object
+	 *
+	 * @var    CMSApplicationInterface
+	 *
+	 * @since  __DEPLOY_VERSION__
+	 */
+	private $application;
+
 	/**
 	 * Constructor
 	 *
@@ -120,6 +130,7 @@ public function __construct(&$subject, $config = array())
 
 		if (property_exists($this, 'app'))
 		{
+			@trigger_error('The application should be injected through setApplication() and requested through getApplication().', E_USER_DEPRECATED);
 			$reflection = new \ReflectionClass($this);
 			$appProperty = $reflection->getProperty('app');
 
@@ -131,6 +142,7 @@ public function __construct(&$subject, $config = array())
 
 		if (property_exists($this, 'db'))
 		{
+			@trigger_error('The database should be injected through the DatabaseAwareInterface and trait.', E_USER_DEPRECATED);
 			$reflection = new \ReflectionClass($this);
 			$dbProperty = $reflection->getProperty('db');
 
@@ -162,7 +174,7 @@ public function loadLanguage($extension = '', $basePath = JPATH_ADMINISTRATOR)
 		}
 
 		$extension = strtolower($extension);
-		$lang      = Factory::getLanguage();
+		$lang      = $this->getApplication() ? $this->getApplication()->getLanguage() : Factory::getLanguage();
 
 		// If language already loaded, don't load it again.
 		if ($lang->getPaths($extension))
@@ -174,6 +186,35 @@ public function loadLanguage($extension = '', $basePath = JPATH_ADMINISTRATOR)
 			|| $lang->load($extension, JPATH_PLUGINS . '/' . $this->_type . '/' . $this->_name);
 	}
 
+	/**
+	 * Translates the given key with the local applications language. If arguments are available, then
+	 * injects them into the translated string.
+	 *
+	 * @param   string   $key        The key to translate
+	 * @param   mixed[]  $arguments  The arguments
+	 *
+	 * @return  string  The translated string
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 *
+	 * @see     sprintf
+	 */
+	protected function translate(string $key): string
+	{
+		$language = $this->getApplication()->getLanguage();
+
+		$arguments = \func_get_args();
+
+		if (count($arguments) > 1)
+		{
+			$arguments[0] = $language->_($key);
+
+			return \call_user_func_array('sprintf', $arguments);
+		}
+
+		return $language->_($key);
+	}
+
 	/**
 	 * Registers legacy Listeners to the Dispatcher, emulating how plugins worked under Joomla! 3.x and below.
 	 *
@@ -359,4 +400,30 @@ private function parameterImplementsEventInterface(\ReflectionParameter $paramet
 
 		return false;
 	}
+
+	/**
+	 * Returns the internal application or null when not set.
+	 *
+	 * @return  CMSApplicationInterface|null
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	protected function getApplication(): ?CMSApplicationInterface
+	{
+		return $this->application;
+	}
+
+	/**
+	 * Sets the application to use.
+	 *
+	 * @param   CMSApplicationInterface  $application  The application
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function setApplication(CMSApplicationInterface $application): void
+	{
+		$this->application = $application;
+	}
 }
diff --git a/plugins/actionlog/joomla/services/provider.php b/plugins/actionlog/joomla/services/provider.php
index c1b3b716b15ff..231349af8eff1 100644
--- a/plugins/actionlog/joomla/services/provider.php
+++ b/plugins/actionlog/joomla/services/provider.php
@@ -10,6 +10,7 @@
 defined('_JEXEC') or die;
 
 use Joomla\CMS\Extension\PluginInterface;
+use Joomla\CMS\Factory;
 use Joomla\CMS\Plugin\PluginHelper;
 use Joomla\Database\DatabaseInterface;
 use Joomla\DI\Container;
@@ -38,6 +39,7 @@ function (Container $container)
 					$container->get(DispatcherInterface::class),
 					(array) PluginHelper::getPlugin('actionlog', 'joomla')
 				);
+				$plugin->setApplication(Factory::getApplication());
 				$plugin->setDatabase($container->get(DatabaseInterface::class));
 
 				return $plugin;
diff --git a/plugins/actionlog/joomla/src/Extension/Joomla.php b/plugins/actionlog/joomla/src/Extension/Joomla.php
index 5545949c5aba5..8aadceee4825b 100644
--- a/plugins/actionlog/joomla/src/Extension/Joomla.php
+++ b/plugins/actionlog/joomla/src/Extension/Joomla.php
@@ -11,7 +11,6 @@
 
 defined('_JEXEC') or die;
 
-use Joomla\CMS\Application\CMSApplicationInterface;
 use Joomla\CMS\Component\ComponentHelper;
 use Joomla\CMS\Factory;
 use Joomla\CMS\Installer\Installer;
@@ -36,14 +35,6 @@ final class Joomla extends ActionLogPlugin
 {
 	use DatabaseAwareTrait;
 
-	/**
-	 * Application object.
-	 *
-	 * @var    CMSApplicationInterface
-	 * @since  4.2.0
-	 */
-	protected $app;
-
 	/**
 	 * Array of loggable extensions.
 	 *
@@ -144,7 +135,7 @@ public function onContentAfterSave($context, $article, $isNew): void
 		}
 
 		// If the content type doesn't have its own language key, use default language key
-		if (!$this->app->getLanguage()->hasKey($messageLanguageKey))
+		if (!$this->getApplication()->getLanguage()->hasKey($messageLanguageKey))
 		{
 			$messageLanguageKey = $defaultLanguageKey;
 		}
@@ -176,7 +167,7 @@ public function onContentAfterSave($context, $article, $isNew): void
 	 */
 	public function onContentAfterDelete($context, $article): void
 	{
-		$option = $this->app->input->get('option');
+		$option = $this->getApplication()->input->get('option');
 
 		if (!$this->checkLoggable($option))
 		{
@@ -192,7 +183,7 @@ public function onContentAfterDelete($context, $article): void
 		}
 
 		// If the content type has its own language key, use it, otherwise, use default language key
-		if ($this->app->getLanguage()->hasKey(strtoupper($params->text_prefix . '_' . $params->type_title . '_DELETED')))
+		if ($this->getApplication()->getLanguage()->hasKey(strtoupper($params->text_prefix . '_' . $params->type_title . '_DELETED')))
 		{
 			$messageLanguageKey = $params->text_prefix . '_' . $params->type_title . '_DELETED';
 		}
@@ -228,7 +219,7 @@ public function onContentAfterDelete($context, $article): void
 	 */
 	public function onContentChangeState($context, $pks, $value)
 	{
-		$option = $this->app->input->getCmd('option');
+		$option = $this->getApplication()->input->getCmd('option');
 
 		if (!$this->checkLoggable($option))
 		{
@@ -275,7 +266,7 @@ public function onContentChangeState($context, $pks, $value)
 		}
 
 		// If the content type doesn't have its own language key, use default language key
-		if (!$this->app->getLanguage()->hasKey($messageLanguageKey))
+		if (!$this->getApplication()->getLanguage()->hasKey($messageLanguageKey))
 		{
 			$messageLanguageKey = $defaultLanguageKey;
 		}
@@ -326,7 +317,7 @@ public function onContentChangeState($context, $pks, $value)
 	 */
 	public function onApplicationAfterSave($config): void
 	{
-		$option = $this->app->input->getCmd('option');
+		$option = $this->getApplication()->input->getCmd('option');
 
 		if (!$this->checkLoggable($option))
 		{
@@ -360,7 +351,7 @@ public function onApplicationAfterSave($config): void
 	 */
 	public function onExtensionAfterInstall($installer, $eid)
 	{
-		$context = $this->app->input->get('option');
+		$context = $this->getApplication()->input->get('option');
 
 		if (!$this->checkLoggable($context))
 		{
@@ -377,7 +368,7 @@ public function onExtensionAfterInstall($installer, $eid)
 		$extensionType = $manifest->attributes()->type;
 
 		// If the extension type has its own language key, use it, otherwise, use default language key
-		if ($this->app->getLanguage()->hasKey(strtoupper('PLG_ACTIONLOG_JOOMLA_' . $extensionType . '_INSTALLED')))
+		if ($this->getApplication()->getLanguage()->hasKey(strtoupper('PLG_ACTIONLOG_JOOMLA_' . $extensionType . '_INSTALLED')))
 		{
 			$messageLanguageKey = 'PLG_ACTIONLOG_JOOMLA_' . $extensionType . '_INSTALLED';
 		}
@@ -412,7 +403,7 @@ public function onExtensionAfterInstall($installer, $eid)
 	 */
 	public function onExtensionAfterUninstall($installer, $eid, $result)
 	{
-		$context = $this->app->input->get('option');
+		$context = $this->getApplication()->input->get('option');
 
 		if (!$this->checkLoggable($context))
 		{
@@ -435,7 +426,7 @@ public function onExtensionAfterUninstall($installer, $eid, $result)
 		$extensionType = $manifest->attributes()->type;
 
 		// If the extension type has its own language key, use it, otherwise, use default language key
-		if ($this->app->getLanguage()->hasKey(strtoupper('PLG_ACTIONLOG_JOOMLA_' . $extensionType . '_UNINSTALLED')))
+		if ($this->getApplication()->getLanguage()->hasKey(strtoupper('PLG_ACTIONLOG_JOOMLA_' . $extensionType . '_UNINSTALLED')))
 		{
 			$messageLanguageKey = 'PLG_ACTIONLOG_JOOMLA_' . $extensionType . '_UNINSTALLED';
 		}
@@ -469,7 +460,7 @@ public function onExtensionAfterUninstall($installer, $eid, $result)
 	 */
 	public function onExtensionAfterUpdate($installer, $eid)
 	{
-		$context = $this->app->input->get('option');
+		$context = $this->getApplication()->input->get('option');
 
 		if (!$this->checkLoggable($context))
 		{
@@ -486,7 +477,7 @@ public function onExtensionAfterUpdate($installer, $eid)
 		$extensionType = $manifest->attributes()->type;
 
 		// If the extension type has its own language key, use it, otherwise, use default language key
-		if ($this->app->getLanguage()->hasKey('PLG_ACTIONLOG_JOOMLA_' . $extensionType . '_UPDATED'))
+		if ($this->getApplication()->getLanguage()->hasKey('PLG_ACTIONLOG_JOOMLA_' . $extensionType . '_UPDATED'))
 		{
 			$messageLanguageKey = 'PLG_ACTIONLOG_JOOMLA_' . $extensionType . '_UPDATED';
 		}
@@ -520,7 +511,7 @@ public function onExtensionAfterUpdate($installer, $eid)
 	 */
 	public function onExtensionAfterSave($context, $table, $isNew): void
 	{
-		$option = $this->app->input->getCmd('option');
+		$option = $this->getApplication()->input->getCmd('option');
 
 		if ($table->get('module') != null)
 		{
@@ -554,7 +545,7 @@ public function onExtensionAfterSave($context, $table, $isNew): void
 		}
 
 		// If the extension type doesn't have it own language key, use default language key
-		if (!$this->app->getLanguage()->hasKey($messageLanguageKey))
+		if (!$this->getApplication()->getLanguage()->hasKey($messageLanguageKey))
 		{
 			$messageLanguageKey = $defaultLanguageKey;
 		}
@@ -584,7 +575,7 @@ public function onExtensionAfterSave($context, $table, $isNew): void
 	 */
 	public function onExtensionAfterDelete($context, $table): void
 	{
-		if (!$this->checkLoggable($this->app->input->get('option')))
+		if (!$this->checkLoggable($this->getApplication()->input->get('option')))
 		{
 			return;
 		}
@@ -625,8 +616,8 @@ public function onExtensionAfterDelete($context, $table): void
 	 */
 	public function onUserAfterSave($user, $isnew, $success, $msg): void
 	{
-		$context = $this->app->input->get('option');
-		$task    = $this->app->input->post->get('task');
+		$context = $this->getApplication()->input->get('option');
+		$task    = $this->getApplication()->input->post->get('task');
 
 		if (!$this->checkLoggable($context))
 		{
@@ -704,7 +695,7 @@ public function onUserAfterSave($user, $isnew, $success, $msg): void
 	 */
 	public function onUserAfterDelete($user, $success, $msg): void
 	{
-		$context = $this->app->input->get('option');
+		$context = $this->getApplication()->input->get('option');
 
 		if (!$this->checkLoggable($context))
 		{
@@ -739,7 +730,7 @@ public function onUserAfterDelete($user, $success, $msg): void
 	public function onUserAfterSaveGroup($context, $table, $isNew): void
 	{
 		// Override context (com_users.group) with the component context (com_users) to pass the checkLoggable
-		$context = $this->app->input->get('option');
+		$context = $this->getApplication()->input->get('option');
 
 		if (!$this->checkLoggable($context))
 		{
@@ -783,7 +774,7 @@ public function onUserAfterSaveGroup($context, $table, $isNew): void
 	 */
 	public function onUserAfterDeleteGroup($group, $success, $msg): void
 	{
-		$context = $this->app->input->get('option');
+		$context = $this->getApplication()->input->get('option');
 
 		if (!$this->checkLoggable($context))
 		{
@@ -833,7 +824,7 @@ public function onUserAfterLogin($options)
 			'userid'      => $loggedInUser->id,
 			'username'    => $loggedInUser->username,
 			'accountlink' => 'index.php?option=com_users&task=user.edit&id=' . $loggedInUser->id,
-			'app'         => 'PLG_ACTIONLOG_JOOMLA_APPLICATION_' . $this->app->getName(),
+			'app'         => 'PLG_ACTIONLOG_JOOMLA_APPLICATION_' . $this->getApplication()->getName(),
 		);
 
 		$this->addLog(array($message), $messageLanguageKey, $context, $loggedInUser->id);
@@ -889,7 +880,7 @@ public function onUserLoginFailure($response)
 			'userid'      => $loggedInUser->id,
 			'username'    => $loggedInUser->username,
 			'accountlink' => 'index.php?option=com_users&task=user.edit&id=' . $loggedInUser->id,
-			'app'         => 'PLG_ACTIONLOG_JOOMLA_APPLICATION_' . $this->app->getName(),
+			'app'         => 'PLG_ACTIONLOG_JOOMLA_APPLICATION_' . $this->getApplication()->getName(),
 		);
 
 		$this->addLog(array($message), $messageLanguageKey, $context, $loggedInUser->id);
@@ -929,7 +920,7 @@ public function onUserLogout($user, $options = array())
 			'userid'      => $loggedOutUser->id,
 			'username'    => $loggedOutUser->username,
 			'accountlink' => 'index.php?option=com_users&task=user.edit&id=' . $loggedOutUser->id,
-			'app'         => 'PLG_ACTIONLOG_JOOMLA_APPLICATION_' . $this->app->getName(),
+			'app'         => 'PLG_ACTIONLOG_JOOMLA_APPLICATION_' . $this->getApplication()->getName(),
 		);
 
 		$this->addLog(array($message), $messageLanguageKey, $context);
@@ -962,7 +953,7 @@ protected function checkLoggable($extension)
 	 */
 	public function onUserAfterRemind($user)
 	{
-		$context = $this->app->input->get('option');
+		$context = $this->getApplication()->input->get('option');
 
 		if (!$this->checkLoggable($context))
 		{
@@ -1032,7 +1023,7 @@ public function onAfterCheckin($table)
 	 */
 	public function onAfterLogPurge($group = '')
 	{
-		$context = $this->app->input->get('option');
+		$context = $this->getApplication()->input->get('option');
 		$user    = Factory::getUser();
 		$message = array(
 			'action'      => 'actionlogs',
@@ -1060,7 +1051,7 @@ public function onAfterLogPurge($group = '')
 	 */
 	public function onAfterLogExport($group = '')
 	{
-		$context = $this->app->input->get('option');
+		$context = $this->getApplication()->input->get('option');
 		$user    = Factory::getUser();
 		$message = array(
 			'action'      => 'actionlogs',
@@ -1088,7 +1079,7 @@ public function onAfterLogExport($group = '')
 	 */
 	public function onAfterPurge($group = 'all')
 	{
-		$context = $this->app->input->get('option');
+		$context = $this->getApplication()->input->get('option');
 		$user    = Factory::getUser();
 
 		if (!$this->checkLoggable($context))
@@ -1121,7 +1112,7 @@ public function onAfterPurge($group = 'all')
 	 */
 	public function onAfterDispatch()
 	{
-		if (!$this->app->isClient('api'))
+		if (!$this->getApplication()->isClient('api'))
 		{
 			return;
 		}
@@ -1131,27 +1122,27 @@ public function onAfterDispatch()
 			return;
 		}
 
-		$verb = $this->app->input->getMethod();
+		$verb = $this->getApplication()->input->getMethod();
 
 		if (!in_array($verb, $this->loggableVerbs))
 		{
 			return;
 		}
 
-		$context = $this->app->input->get('option');
+		$context = $this->getApplication()->input->get('option');
 
 		if (!$this->checkLoggable($context))
 		{
 			return;
 		}
 
-		$user = $this->app->getIdentity();
+		$user = $this->getApplication()->getIdentity();
 		$message = array(
 			'action'      => 'API',
 			'verb'        => $verb,
 			'username'    => $user->username,
 			'accountlink' => 'index.php?option=com_users&task=user.edit&id=' . $user->id,
-			'url'         => htmlspecialchars(urldecode($this->app->get('uri.route')), ENT_QUOTES, 'UTF-8'),
+			'url'         => htmlspecialchars(urldecode($this->getApplication()->get('uri.route')), ENT_QUOTES, 'UTF-8'),
 		);
 		$this->addLog(array($message), 'PLG_ACTIONLOG_JOOMLA_API', $context, $user->id);
 	}
@@ -1169,12 +1160,12 @@ public function onAfterDispatch()
 	 */
 	public function onJoomlaAfterUpdate($oldVersion = null)
 	{
-		$context = $this->app->input->get('option');
+		$context = $this->getApplication()->input->get('option');
 		$user    = Factory::getUser();
 
 		if (empty($oldVersion))
 		{
-			$oldVersion = $this->app->getLanguage()->_('JLIB_UNKNOWN');
+			$oldVersion = $this->getApplication()->getLanguage()->_('JLIB_UNKNOWN');
 		}
 
 		$message = array(
@@ -1203,7 +1194,7 @@ public function onJoomlaAfterUpdate($oldVersion = null)
 	 */
 	private function getActionLogParams($context): ?stdClass
 	{
-		$component = $this->app->bootComponent('actionlogs');
+		$component = $this->getApplication()->bootComponent('actionlogs');
 
 		if (!$component instanceof MVCFactoryServiceInterface)
 		{
diff --git a/plugins/api-authentication/basic/services/provider.php b/plugins/api-authentication/basic/services/provider.php
index 93551f1ecfc70..750203eb57e4d 100644
--- a/plugins/api-authentication/basic/services/provider.php
+++ b/plugins/api-authentication/basic/services/provider.php
@@ -10,6 +10,7 @@
 defined('_JEXEC') or die;
 
 use Joomla\CMS\Extension\PluginInterface;
+use Joomla\CMS\Factory;
 use Joomla\CMS\Plugin\PluginHelper;
 use Joomla\CMS\User\UserFactoryInterface;
 use Joomla\Database\DatabaseInterface;
@@ -40,6 +41,7 @@ function (Container $container)
 					(array) PluginHelper::getPlugin('api-authentication', 'basic'),
 					$container->get(UserFactoryInterface::class)
 				);
+				$plugin->setApplication(Factory::getApplication());
 				$plugin->setDatabase($container->get(DatabaseInterface::class));
 
 				return $plugin;
diff --git a/plugins/api-authentication/basic/src/Extension/Basic.php b/plugins/api-authentication/basic/src/Extension/Basic.php
index afed7bd380c7a..96cfc74ebdc53 100644
--- a/plugins/api-authentication/basic/src/Extension/Basic.php
+++ b/plugins/api-authentication/basic/src/Extension/Basic.php
@@ -11,7 +11,6 @@
 
 defined('_JEXEC') or die;
 
-use Joomla\CMS\Application\CMSApplicationInterface;
 use Joomla\CMS\Authentication\Authentication;
 use Joomla\CMS\Plugin\CMSPlugin;
 use Joomla\CMS\User\UserFactoryInterface;
@@ -28,14 +27,6 @@ final class Basic extends CMSPlugin
 {
 	use DatabaseAwareTrait;
 
-	/**
-	 * The application object
-	 *
-	 * @var    CMSApplicationInterface
-	 * @since  4.0.0
-	 */
-	protected $app;
-
 	/**
 	 * The user factory
 	 *
@@ -75,13 +66,13 @@ public function onUserAuthenticate($credentials, $options, &$response)
 	{
 		$response->type = 'Basic';
 
-		$username = $this->app->input->server->get('PHP_AUTH_USER', '', 'USERNAME');
-		$password = $this->app->input->server->get('PHP_AUTH_PW', '', 'RAW');
+		$username = $this->getApplication()->input->server->get('PHP_AUTH_USER', '', 'USERNAME');
+		$password = $this->getApplication()->input->server->get('PHP_AUTH_PW', '', 'RAW');
 
 		if ($password === '')
 		{
 			$response->status        = Authentication::STATUS_FAILURE;
-			$response->error_message = $this->app->getLanguage()->_('JGLOBAL_AUTH_EMPTY_PASS_NOT_ALLOWED');
+			$response->error_message = $this->translate('JGLOBAL_AUTH_EMPTY_PASS_NOT_ALLOWED');
 
 			return;
 		}
@@ -108,7 +99,7 @@ public function onUserAuthenticate($credentials, $options, &$response)
 				$response->fullname = $user->name;
 				$response->username = $username;
 
-				if ($this->app->isClient('administrator'))
+				if ($this->getApplication()->isClient('administrator'))
 				{
 					$response->language = $user->getParam('admin_language');
 				}
@@ -125,7 +116,7 @@ public function onUserAuthenticate($credentials, $options, &$response)
 			{
 				// Invalid password
 				$response->status        = Authentication::STATUS_FAILURE;
-				$response->error_message = $this->app->getLanguage()->_('JGLOBAL_AUTH_INVALID_PASS');
+				$response->error_message = $this->translate('JGLOBAL_AUTH_INVALID_PASS');
 			}
 		}
 		else
@@ -136,7 +127,7 @@ public function onUserAuthenticate($credentials, $options, &$response)
 
 			// Invalid user
 			$response->status        = Authentication::STATUS_FAILURE;
-			$response->error_message = $this->app->getLanguage()->_('JGLOBAL_AUTH_NO_USER');
+			$response->error_message = $this->translate('JGLOBAL_AUTH_NO_USER');
 		}
 	}
 }
diff --git a/plugins/api-authentication/token/services/provider.php b/plugins/api-authentication/token/services/provider.php
index 11efa5d5f29d3..6826d305b65f8 100644
--- a/plugins/api-authentication/token/services/provider.php
+++ b/plugins/api-authentication/token/services/provider.php
@@ -10,6 +10,7 @@
 defined('_JEXEC') or die;
 
 use Joomla\CMS\Extension\PluginInterface;
+use Joomla\CMS\Factory;
 use Joomla\CMS\Plugin\PluginHelper;
 use Joomla\CMS\User\UserFactoryInterface;
 use Joomla\Database\DatabaseInterface;
@@ -42,6 +43,7 @@ function (Container $container)
 					$container->get(UserFactoryInterface::class),
 					new InputFilter
 				);
+				$plugin->setApplication(Factory::getApplication());
 				$plugin->setDatabase($container->get(DatabaseInterface::class));
 
 				return $plugin;
diff --git a/plugins/api-authentication/token/src/Extension/Token.php b/plugins/api-authentication/token/src/Extension/Token.php
index 63ab2c8203b4d..e268e2eb21ed7 100644
--- a/plugins/api-authentication/token/src/Extension/Token.php
+++ b/plugins/api-authentication/token/src/Extension/Token.php
@@ -11,7 +11,6 @@
 
 defined('_JEXEC') or die;
 
-use Joomla\CMS\Application\ApiApplication;
 use Joomla\CMS\Authentication\Authentication;
 use Joomla\CMS\Crypt\Crypt;
 use Joomla\CMS\Plugin\CMSPlugin;
@@ -31,14 +30,6 @@ final class Token extends CMSPlugin
 {
 	use DatabaseAwareTrait;
 
-	/**
-	 * The application object
-	 *
-	 * @var    CMSApplicationInterface
-	 * @since  4.0.0
-	 */
-	protected $app;
-
 	/**
 	 * The prefix of the user profile keys, without the dot.
 	 *
@@ -105,7 +96,7 @@ public function onUserAuthenticate($credentials, $options, &$response): void
 		// Default response is authentication failure.
 		$response->type          = 'Token';
 		$response->status        = Authentication::STATUS_FAILURE;
-		$response->error_message = $this->app->getLanguage()->_('JGLOBAL_AUTH_FAIL');
+		$response->error_message = $this->translate('JGLOBAL_AUTH_FAIL');
 
 		/**
 		 * First look for an HTTP Authorization header with the following format:
@@ -113,7 +104,7 @@ public function onUserAuthenticate($credentials, $options, &$response): void
 		 * Do keep in mind that Bearer is **case-sensitive**. Whitespace between Bearer and the
 		 * token, as well as any whitespace following the token is discarded.
 		 */
-		$authHeader  = $this->app->input->server->get('HTTP_AUTHORIZATION', '', 'string');
+		$authHeader  = $this->getApplication()->input->server->get('HTTP_AUTHORIZATION', '', 'string');
 		$tokenString = '';
 
 		// Apache specific fixes. See https://github.com/symfony/symfony/issues/19693
@@ -137,7 +128,7 @@ public function onUserAuthenticate($credentials, $options, &$response): void
 
 		if (empty($tokenString))
 		{
-			$tokenString = $this->app->input->server->get('HTTP_X_JOOMLA_TOKEN', '', 'string');
+			$tokenString = $this->getApplication()->input->server->get('HTTP_X_JOOMLA_TOKEN', '', 'string');
 		}
 
 		// No token: authentication failure
@@ -182,7 +173,7 @@ public function onUserAuthenticate($credentials, $options, &$response): void
 		 */
 		try
 		{
-			$siteSecret = $this->app->get('secret');
+			$siteSecret = $this->getApplication()->get('secret');
 		}
 		catch (\Exception $e)
 		{
@@ -343,7 +334,8 @@ private function isTokenEnabledForUser(int $userId): bool
 	private function getPluginParameter(string $folder, string $plugin, string $param, $default = null)
 	{
 		/** @var PluginModel $model */
-		$model = $this->app->bootComponent('plugins')->getMVCFactory()->createModel('Plugin', 'Administrator', ['ignore_request' => true]);
+		$model = $this->getApplication()->bootComponent('plugins')
+			->getMVCFactory()->createModel('Plugin', 'Administrator', ['ignore_request' => true]);
 
 		$pluginObject = $model->getItem(['folder' => $folder, 'element' => $plugin]);
 
diff --git a/plugins/behaviour/versionable/services/provider.php b/plugins/behaviour/versionable/services/provider.php
index 621d7650b4591..36a84b8ae7902 100644
--- a/plugins/behaviour/versionable/services/provider.php
+++ b/plugins/behaviour/versionable/services/provider.php
@@ -10,6 +10,7 @@
 defined('_JEXEC') or die;
 
 use Joomla\CMS\Extension\PluginInterface;
+use Joomla\CMS\Factory;
 use Joomla\CMS\Helper\CMSHelper;
 use Joomla\CMS\Plugin\PluginHelper;
 use Joomla\DI\Container;
@@ -42,6 +43,7 @@ function (Container $container)
 					new InputFilter,
 					new CMSHelper
 				);
+				$plugin->setApplication(Factory::getApplication());
 
 				return $plugin;
 			}
diff --git a/plugins/behaviour/versionable/src/Extension/Versionable.php b/plugins/behaviour/versionable/src/Extension/Versionable.php
index 990d96bbae401..7cb6d41d5312e 100644
--- a/plugins/behaviour/versionable/src/Extension/Versionable.php
+++ b/plugins/behaviour/versionable/src/Extension/Versionable.php
@@ -11,7 +11,6 @@
 
 defined('_JEXEC') or die;
 
-use Joomla\CMS\Application\CMSApplicationInterface;
 use Joomla\CMS\Component\ComponentHelper;
 use Joomla\CMS\Event\Table\AfterStoreEvent;
 use Joomla\CMS\Event\Table\BeforeDeleteEvent;
@@ -47,14 +46,6 @@ public static function getSubscribedEvents(): array
 		];
 	}
 
-	/**
-	 * The application object
-	 *
-	 * @var    CMSApplicationInterface
-	 * @since  __DEPLOY_VERSION__
-	 */
-	protected $app;
-
 	/**
 	 * The input filter
 	 *
@@ -126,7 +117,7 @@ public function onTableAfterStore(AfterStoreEvent $event)
 
 		$id     = $table->getId();
 		$data   = $this->helper->getDataObject($table);
-		$input  = $this->app->input;
+		$input  = $this->getApplication()->input;
 		$jform  = $input->get('jform', array(), 'array');
 		$versionNote = '';
 
diff --git a/plugins/multifactorauth/email/services/provider.php b/plugins/multifactorauth/email/services/provider.php
index a4417d8122f7b..480381df74d63 100644
--- a/plugins/multifactorauth/email/services/provider.php
+++ b/plugins/multifactorauth/email/services/provider.php
@@ -10,6 +10,7 @@
 defined('_JEXEC') || die;
 
 use Joomla\CMS\Extension\PluginInterface;
+use Joomla\CMS\Factory;
 use Joomla\CMS\Plugin\PluginHelper;
 use Joomla\DI\Container;
 use Joomla\DI\ServiceProviderInterface;
@@ -35,7 +36,10 @@ function (Container $container) {
 				$config  = (array) PluginHelper::getPlugin('multifactorauth', 'email');
 				$subject = $container->get(DispatcherInterface::class);
 
-				return new Email($subject, $config);
+				$plugin = new Email($subject, $config);
+				$plugin->setApplication(Factory::getApplication());
+
+				return $plugin;
 			}
 		);
 	}
diff --git a/plugins/multifactorauth/email/src/Extension/Email.php b/plugins/multifactorauth/email/src/Extension/Email.php
index 95e3cc3d561e7..61dba2373b0c1 100644
--- a/plugins/multifactorauth/email/src/Extension/Email.php
+++ b/plugins/multifactorauth/email/src/Extension/Email.php
@@ -10,7 +10,6 @@
 namespace Joomla\Plugin\Multifactorauth\Email\Extension;
 
 use Exception;
-use Joomla\CMS\Application\CMSApplication;
 use Joomla\CMS\Encrypt\Totp;
 use Joomla\CMS\Event\MultiFactor\BeforeDisplayMethods;
 use Joomla\CMS\Event\MultiFactor\Captive;
@@ -63,14 +62,6 @@ class Email extends CMSPlugin implements SubscriberInterface
 	 */
 	private const SECRET_KEY_LENGTH = 20;
 
-	/**
-	 * The CMS application we are running under
-	 *
-	 * @var   CMSApplication
-	 * @since 4.2.0
-	 */
-	protected $app;
-
 	/**
 	 * Forbid registration of legacy (Joomla 3) event listeners.
 	 *
@@ -235,7 +226,7 @@ public function onUserMultifactorGetSetup(GetSetup $event): void
 		$isKeyAlreadySetup = !empty($key);
 
 		// If there's a key in the session use that instead.
-		$session = $this->app->getSession();
+		$session = $this->getApplication()->getSession();
 		$session->get('plg_multifactorauth_email.emailcode.key', $key);
 
 		// Initialize objects
@@ -320,7 +311,7 @@ public function onUserMultifactorSaveSetup(SaveSetup $event): void
 		$options           = $this->decodeRecordOptions($record);
 		$key               = $options['key'] ?? '';
 		$isKeyAlreadySetup = !empty($key);
-		$session           = $this->app->getSession();
+		$session           = $this->getApplication()->getSession();
 
 		// If there is no key in the options fetch one from the session
 		if (empty($key))
@@ -479,7 +470,7 @@ function (MfaTable $record)
 		try
 		{
 			/** @var MVCFactoryInterface $factory */
-			$factory = $this->app->bootComponent('com_users')->getMVCFactory();
+			$factory = $this->getApplication()->bootComponent('com_users')->getMVCFactory();
 			/** @var MfaTable $record */
 			$record = $factory->createTable('Mfa', 'Administrator');
 			$record->reset();
@@ -546,7 +537,7 @@ private function sendCode(string $key, ?User $user = null)
 		// Make sure we have a user
 		if (!is_object($user) || !($user instanceof User))
 		{
-			$user = $this->app->getIdentity()
+			$user = $this->getApplication()->getIdentity()
 				?: Factory::getContainer()->get(UserFactoryInterface::class)->loadUserById(0);
 		}
 
@@ -566,7 +557,7 @@ private function sendCode(string $key, ?User $user = null)
 
 		$replacements = [
 			'code'     => $code,
-			'sitename' => $this->app->get('sitename'),
+			'sitename' => $this->getApplication()->get('sitename'),
 			'siteurl'  => Uri::base(),
 			'username' => $user->username,
 			'email'    => $user->email,
@@ -575,7 +566,7 @@ private function sendCode(string $key, ?User $user = null)
 
 		try
 		{
-			$jLanguage = $this->app->getLanguage();
+			$jLanguage = $this->getApplication()->getLanguage();
 			$mailer = new MailTemplate('plg_multifactorauth_email.mail', $jLanguage->getTag());
 			$mailer->addRecipient($user->email, $user->name);
 			$mailer->addTemplateData($replacements);
@@ -590,7 +581,7 @@ private function sendCode(string $key, ?User $user = null)
 			}
 			catch (RuntimeException $exception)
 			{
-				$this->app->enqueueMessage(Text::_($exception->errorMessage()), 'warning');
+				$this->getApplication()->enqueueMessage(Text::_($exception->errorMessage()), 'warning');
 			}
 		}
 
@@ -624,7 +615,7 @@ private function sendCode(string $key, ?User $user = null)
 			}
 			catch (RuntimeException $exception)
 			{
-				$this->app->enqueueMessage(Text::_($exception->errorMessage()), 'warning');
+				$this->getApplication()->enqueueMessage(Text::_($exception->errorMessage()), 'warning');
 			}
 		}
 	}
diff --git a/plugins/multifactorauth/fixed/src/Extension/Fixed.php b/plugins/multifactorauth/fixed/src/Extension/Fixed.php
index 0d9b9953dafb4..51e88928743bf 100644
--- a/plugins/multifactorauth/fixed/src/Extension/Fixed.php
+++ b/plugins/multifactorauth/fixed/src/Extension/Fixed.php
@@ -9,7 +9,6 @@
 
 namespace Joomla\Plugin\Multifactorauth\Fixed\Extension;
 
-use Joomla\CMS\Application\CMSApplication;
 use Joomla\CMS\Event\MultiFactor\Captive;
 use Joomla\CMS\Event\MultiFactor\GetMethod;
 use Joomla\CMS\Event\MultiFactor\GetSetup;
@@ -39,14 +38,6 @@
  */
 class Fixed extends CMSPlugin implements SubscriberInterface
 {
-	/**
-	 * The application we are running under.
-	 *
-	 * @var    CMSApplication
-	 * @since  4.2.0
-	 */
-	protected $app;
-
 	/**
 	 * Affects constructor behavior. If true, language files will be loaded automatically.
 	 *
diff --git a/plugins/multifactorauth/totp/services/provider.php b/plugins/multifactorauth/totp/services/provider.php
index 5c681609f05d2..4c74f9f94cf41 100644
--- a/plugins/multifactorauth/totp/services/provider.php
+++ b/plugins/multifactorauth/totp/services/provider.php
@@ -10,6 +10,7 @@
 defined('_JEXEC') || die;
 
 use Joomla\CMS\Extension\PluginInterface;
+use Joomla\CMS\Factory;
 use Joomla\CMS\Plugin\PluginHelper;
 use Joomla\DI\Container;
 use Joomla\DI\ServiceProviderInterface;
@@ -35,7 +36,10 @@ function (Container $container) {
 				$config  = (array) PluginHelper::getPlugin('multifactorauth', 'totp');
 				$subject = $container->get(DispatcherInterface::class);
 
-				return new Totp($subject, $config);
+				$plugin = new Totp($subject, $config);
+				$plugin->setApplication(Factory::getApplication());
+
+				return $plugin;
 			}
 		);
 	}
diff --git a/plugins/multifactorauth/totp/src/Extension/Totp.php b/plugins/multifactorauth/totp/src/Extension/Totp.php
index 4706a8ee3489e..1b08901e71c6a 100644
--- a/plugins/multifactorauth/totp/src/Extension/Totp.php
+++ b/plugins/multifactorauth/totp/src/Extension/Totp.php
@@ -9,7 +9,6 @@
 
 namespace Joomla\Plugin\Multifactorauth\Totp\Extension;
 
-use Joomla\CMS\Application\CMSApplication;
 use Joomla\CMS\Encrypt\Totp as TotpHelper;
 use Joomla\CMS\Event\MultiFactor\Captive;
 use Joomla\CMS\Event\MultiFactor\GetMethod;
@@ -37,14 +36,6 @@
  */
 class Totp extends CMSPlugin implements SubscriberInterface
 {
-	/**
-	 * The application we are running under.
-	 *
-	 * @var    CMSApplication
-	 * @since  4.2.0
-	 */
-	protected $app;
-
 	/**
 	 * Affects constructor behavior. If true, language files will be loaded automatically.
 	 *
@@ -187,7 +178,7 @@ public function onUserMultifactorGetSetup(GetSetup $event): void
 		// Load the options from the record (if any)
 		$options      = $this->decodeRecordOptions($record);
 		$key          = $options['key'] ?? '';
-		$session      = $this->app->getSession();
+		$session      = $this->getApplication()->getSession();
 		$isConfigured = !empty($key);
 
 		// If there's a key in the session use that instead.
@@ -210,7 +201,7 @@ public function onUserMultifactorGetSetup(GetSetup $event): void
 		$user     = Factory::getContainer()->get(UserFactoryInterface::class)->loadUserById($record->user_id);
 		$hostname = Uri::getInstance()->toString(['host']);
 		$otpURL   = sprintf("otpauth://totp/%s@%s?secret=%s", $user->username, $hostname, $key);
-		$document = $this->app->getDocument();
+		$document = $this->getApplication()->getDocument();
 		$wam      = $document->getWebAssetManager();
 
 		$document->addScriptOptions('plg_multifactorauth_totp.totp.qr', $otpURL);
@@ -277,7 +268,7 @@ public function onUserMultifactorSaveSetup(SaveSetup $event): void
 		$options    = $this->decodeRecordOptions($record);
 		$optionsKey = $options['key'] ?? '';
 		$key        = $optionsKey;
-		$session    = $this->app->getSession();
+		$session    = $this->getApplication()->getSession();
 
 		// If there is no key in the options fetch one from the session
 		if (empty($key))
diff --git a/plugins/multifactorauth/webauthn/services/provider.php b/plugins/multifactorauth/webauthn/services/provider.php
index f639252976259..079bfebacde8e 100644
--- a/plugins/multifactorauth/webauthn/services/provider.php
+++ b/plugins/multifactorauth/webauthn/services/provider.php
@@ -10,6 +10,7 @@
 defined('_JEXEC') || die;
 
 use Joomla\CMS\Extension\PluginInterface;
+use Joomla\CMS\Factory;
 use Joomla\CMS\Plugin\PluginHelper;
 use Joomla\DI\Container;
 use Joomla\DI\ServiceProviderInterface;
@@ -35,7 +36,10 @@ function (Container $container) {
 				$config  = (array) PluginHelper::getPlugin('multifactorauth', 'webauthn');
 				$subject = $container->get(DispatcherInterface::class);
 
-				return new Webauthn($subject, $config);
+				$plugin = new Webauthn($subject, $config);
+				$plugin->setApplication(Factory::getApplication());
+
+				return $plugin;
 			}
 		);
 	}
diff --git a/plugins/multifactorauth/webauthn/src/Extension/Webauthn.php b/plugins/multifactorauth/webauthn/src/Extension/Webauthn.php
index 9c381a3ccc935..5368078c27ec8 100644
--- a/plugins/multifactorauth/webauthn/src/Extension/Webauthn.php
+++ b/plugins/multifactorauth/webauthn/src/Extension/Webauthn.php
@@ -10,9 +10,7 @@
 namespace Joomla\Plugin\Multifactorauth\Webauthn\Extension;
 
 use Exception;
-use Joomla\CMS\Application\AdministratorApplication;
 use Joomla\CMS\Application\CMSApplication;
-use Joomla\CMS\Application\SiteApplication;
 use Joomla\CMS\Event\MultiFactor\Captive;
 use Joomla\CMS\Event\MultiFactor\GetMethod;
 use Joomla\CMS\Event\MultiFactor\GetSetup;
@@ -42,14 +40,6 @@
  */
 class Webauthn extends CMSPlugin implements SubscriberInterface
 {
-	/**
-	 * The application object
-	 *
-	 * @var    CMSApplication|SiteApplication|AdministratorApplication
-	 * @since  4.2.0
-	 */
-	protected $app;
-
 	/**
 	 * Auto-load the plugin's language files
 	 *
@@ -147,7 +137,7 @@ public function onUserMultifactorGetSetup(GetSetup $event): void
 		 */
 		if (!is_array($record->options) || empty($record->options['credentialId'] ?? ''))
 		{
-			$document = $this->app->getDocument();
+			$document = $this->getApplication()->getDocument();
 			$wam      = $document->getWebAssetManager();
 			$wam->getRegistry()->addExtensionRegistryFile('plg_multifactorauth_webauthn');
 
@@ -232,7 +222,7 @@ public function onUserMultifactorSaveSetup(SaveSetup $event): void
 		}
 
 		$code                = $input->get('code', null, 'base64');
-		$session             = $this->app->getSession();
+		$session             = $this->getApplication()->getSession();
 		$registrationRequest = $session->get('plg_multifactorauth_webauthn.publicKeyCredentialCreationOptions', null);
 
 		// If there was no registration request BUT there is a registration response throw an error
@@ -328,10 +318,10 @@ public function onUserMultifactorCaptive(Captive $event): void
 		 * That was fun to debug - for "poke your eyes with a rusty fork" values of fun.
 		 */
 
-		$session          = $this->app->getSession();
+		$session          = $this->getApplication()->getSession();
 		$pkOptionsEncoded = $session->get('plg_multifactorauth_webauthn.publicKeyCredentialRequestOptions', null);
 
-		$force = $this->app->input->getInt('force', 0);
+		$force = $this->getApplication()->input->getInt('force', 0);
 
 		try
 		{
@@ -361,7 +351,7 @@ public function onUserMultifactorCaptive(Captive $event): void
 			$pkRequest = Credentials::requestAssertion($record->user_id);
 		}
 
-		$document = $this->app->getDocument();
+		$document = $this->getApplication()->getDocument();
 		$wam      = $document->getWebAssetManager();
 		$wam->getRegistry()->addExtensionRegistryFile('plg_multifactorauth_webauthn');
 
@@ -461,7 +451,7 @@ public function onUserMultifactorValidate(Validate $event): void
 		{
 			try
 			{
-				$this->app->enqueueMessage($e->getMessage(), 'error');
+				$this->getApplication()->enqueueMessage($e->getMessage(), 'error');
 			}
 			catch (Exception $e)
 			{
diff --git a/plugins/multifactorauth/yubikey/services/provider.php b/plugins/multifactorauth/yubikey/services/provider.php
index 7afd9aea77d64..6fe291868d01b 100644
--- a/plugins/multifactorauth/yubikey/services/provider.php
+++ b/plugins/multifactorauth/yubikey/services/provider.php
@@ -10,6 +10,7 @@
 defined('_JEXEC') || die;
 
 use Joomla\CMS\Extension\PluginInterface;
+use Joomla\CMS\Factory;
 use Joomla\CMS\Plugin\PluginHelper;
 use Joomla\DI\Container;
 use Joomla\DI\ServiceProviderInterface;
@@ -35,7 +36,10 @@ function (Container $container) {
 				$config  = (array) PluginHelper::getPlugin('multifactorauth', 'yubikey');
 				$subject = $container->get(DispatcherInterface::class);
 
-				return new Yubikey($subject, $config);
+				$plugin = new Yubikey($subject, $config);
+				$plugin->setApplication(Factory::getApplication());
+
+				return $plugin;
 			}
 		);
 	}
diff --git a/plugins/multifactorauth/yubikey/src/Extension/Yubikey.php b/plugins/multifactorauth/yubikey/src/Extension/Yubikey.php
index 57f40108dfeef..4ec29787e1794 100644
--- a/plugins/multifactorauth/yubikey/src/Extension/Yubikey.php
+++ b/plugins/multifactorauth/yubikey/src/Extension/Yubikey.php
@@ -10,7 +10,6 @@
 namespace Joomla\Plugin\Multifactorauth\Yubikey\Extension;
 
 use Exception;
-use Joomla\CMS\Application\CMSApplication;
 use Joomla\CMS\Event\MultiFactor\Captive;
 use Joomla\CMS\Event\MultiFactor\GetMethod;
 use Joomla\CMS\Event\MultiFactor\GetSetup;
@@ -37,14 +36,6 @@
  */
 class Yubikey extends CMSPlugin implements SubscriberInterface
 {
-	/**
-	 * The application we are running under.
-	 *
-	 * @var    CMSApplication
-	 * @since  4.2.0
-	 */
-	protected $app;
-
 	/**
 	 * Affects constructor behavior. If true, language files will be loaded automatically.
 	 *
@@ -386,7 +377,7 @@ private function validateYubikeyOtp(string $otp): bool
 		$gotResponse = false;
 
 		$http     = HttpFactory::getHttp();
-		$token    = $this->app->getFormToken();
+		$token    = $this->getApplication()->getFormToken();
 		$nonce    = md5($token . uniqid(random_int(0, mt_getrandmax())));
 		$response = null;
 
diff --git a/plugins/quickicon/joomlaupdate/services/provider.php b/plugins/quickicon/joomlaupdate/services/provider.php
index f47fd38a017e9..59a075a192bf1 100644
--- a/plugins/quickicon/joomlaupdate/services/provider.php
+++ b/plugins/quickicon/joomlaupdate/services/provider.php
@@ -36,11 +36,14 @@ function (Container $container)
 				// @Todo This needs to be changed to a proper factory
 				$plugin = \Joomla\CMS\Plugin\PluginHelper::getPlugin('quickicon', 'joomlaupdate');
 
-				return new Joomlaupdate(
+				$plugin = new Joomlaupdate(
 					$container->get(DispatcherInterface::class),
 					Factory::getApplication()->getDocument(),
 					(array) $plugin
 				);
+				$plugin->setApplication(Factory::getApplication());
+
+				return $plugin;
 			}
 		);
 	}
diff --git a/plugins/quickicon/joomlaupdate/src/Extension/Joomlaupdate.php b/plugins/quickicon/joomlaupdate/src/Extension/Joomlaupdate.php
index eab04cdf218c0..381489cb0b27a 100644
--- a/plugins/quickicon/joomlaupdate/src/Extension/Joomlaupdate.php
+++ b/plugins/quickicon/joomlaupdate/src/Extension/Joomlaupdate.php
@@ -12,7 +12,6 @@
 \defined('_JEXEC') or die;
 
 use Joomla\CMS\Document\Document;
-use Joomla\CMS\Extension\ExtensionHelper;
 use Joomla\CMS\Language\Text;
 use Joomla\CMS\Plugin\CMSPlugin;
 use Joomla\CMS\Session\Session;
@@ -36,14 +35,6 @@ class Joomlaupdate extends CMSPlugin implements SubscriberInterface
 	 */
 	protected $autoloadLanguage = true;
 
-	/**
-	 * Application object.
-	 *
-	 * @var    \Joomla\CMS\Application\CMSApplication
-	 * @since  3.7.0
-	 */
-	protected $app;
-
 	/**
 	 * The document.
 	 *
@@ -101,7 +92,7 @@ public function getCoreUpdateNotification(QuickIconsEvent $event)
 		$context = $event->getContext();
 
 		if ($context !== $this->params->get('context', 'update_quickicon')
-			|| !$this->app->getIdentity()->authorise('core.manage', 'com_joomlaupdate'))
+			|| !$this->getApplication()->getIdentity()->authorise('core.manage', 'com_joomlaupdate'))
 		{
 			return;
 		}
diff --git a/plugins/system/cache/services/provider.php b/plugins/system/cache/services/provider.php
index 4d918b06b2e39..aad575e576d10 100644
--- a/plugins/system/cache/services/provider.php
+++ b/plugins/system/cache/services/provider.php
@@ -11,6 +11,7 @@
 
 use Joomla\CMS\Cache\CacheControllerFactoryInterface;
 use Joomla\CMS\Extension\PluginInterface;
+use Joomla\CMS\Factory;
 use Joomla\CMS\Plugin\PluginHelper;
 use Joomla\CMS\Profiler\Profiler;
 use Joomla\CMS\Router\SiteRouter;
@@ -42,7 +43,10 @@ function (Container $container)
 				$profiler               = (defined('JDEBUG') && JDEBUG) ? Profiler::getInstance('Application') : null;
 				$router                 = $container->has(SiteRouter::class) ? $container->get(SiteRouter::class) : null;
 
-				return new Cache($dispatcher, (array) $plugin, $documentFactory, $cacheControllerFactory, $profiler, $router);
+				$plugin = new Cache($dispatcher, (array) $plugin, $documentFactory, $cacheControllerFactory, $profiler, $router);
+				$plugin->setApplication(Factory::getApplication());
+
+				return $plugin;
 			}
 		);
 	}
diff --git a/plugins/system/cache/src/Extension/Cache.php b/plugins/system/cache/src/Extension/Cache.php
index 0a78beda68cd0..689af89340265 100644
--- a/plugins/system/cache/src/Extension/Cache.php
+++ b/plugins/system/cache/src/Extension/Cache.php
@@ -33,14 +33,6 @@
  */
 final class Cache extends CMSPlugin implements SubscriberInterface
 {
-	/**
-	 * Application object.
-	 *
-	 * @var    CMSApplication
-	 * @since  3.8.0
-	 */
-	protected $app;
-
 	/**
 	 * Cache instance.
 	 *
@@ -159,7 +151,7 @@ public function onAfterRoute(Event $event)
 		// If any `pagecache` plugins return false for onPageCacheSetCaching, do not use the cache.
 		PluginHelper::importPlugin('pagecache');
 
-		$results = $this->app->triggerEvent('onPageCacheSetCaching');
+		$results = $this->getApplication()->triggerEvent('onPageCacheSetCaching');
 
 		$this->getCacheController()->setCaching(!in_array(false, $results, true));
 
@@ -172,28 +164,28 @@ public function onAfterRoute(Event $event)
 		}
 
 		// Set the page content from the cache and output it to the browser.
-		$this->app->setBody($data);
+		$this->getApplication()->setBody($data);
 
-		echo $this->app->toString((bool) $this->app->get('gzip'));
+		echo $this->getApplication()->toString((bool) $this->getApplication()->get('gzip'));
 
 		// Mark afterCache in debug and run debug onAfterRespond events, e.g. show Joomla Debug Console if debug is active.
 		if (JDEBUG)
 		{
 			// Create a document instance and load it into the application.
 			$document = $this->documentFactory
-				->createDocument($this->app->input->get('format', 'html'));
-			$this->app->loadDocument($document);
+				->createDocument($this->getApplication()->input->get('format', 'html'));
+			$this->getApplication()->loadDocument($document);
 
 			if ($this->profiler)
 			{
 				$this->profiler->mark('afterCache');
 			}
 
-			$this->app->triggerEvent('onAfterRespond');
+			$this->getApplication()->triggerEvent('onAfterRespond');
 		}
 
 		// Closes the application.
-		$this->app->close();
+		$this->getApplication()->close();
 	}
 
 	/**
@@ -222,16 +214,15 @@ private function appStateSupportsCaching(): bool
 
 		if ($isSite === null)
 		{
-			$isSite = ($this->app instanceof CMSApplicationInterface)
-				&& $this->app->isClient('site');
-			$isGET  = $this->app->input->getMethod() === 'GET';
+			$isSite = $this->getApplication()->isClient('site');
+			$isGET  = $this->getApplication()->input->getMethod() === 'GET';
 		}
 
 		// Boolean short–circuit evaluation means this returns fast false when $isSite is false.
 		return $isSite
 			&& $isGET
-			&& $this->app->getIdentity()->guest
-			&& empty($this->app->getMessageQueue());
+			&& $this->getApplication()->getIdentity()->guest
+			&& empty($this->getApplication()->getMessageQueue());
 	}
 
 	/**
@@ -275,7 +266,7 @@ private function getCacheKey(): string
 		{
 			PluginHelper::importPlugin('pagecache');
 
-			$parts   = $this->app->triggerEvent('onPageCacheGetKey');
+			$parts   = $this->getApplication()->triggerEvent('onPageCacheGetKey');
 			$parts[] = Uri::getInstance()->toString();
 
 			$key = md5(serialize($parts));
@@ -308,7 +299,7 @@ public function onAfterRender(Event $event)
 		}
 
 		// Disable compression before caching the page.
-		$this->app->set('gzip', false);
+		$this->getApplication()->set('gzip', false);
 	}
 
 	/**
@@ -326,7 +317,7 @@ private function isExcluded(): bool
 		if ($excludedMenuItems)
 		{
 			// Get the current menu item.
-			$active = $this->app->getMenu()->getActive();
+			$active = $this->getApplication()->getMenu()->getActive();
 
 			if ($active && $active->id && in_array((int) $active->id, (array) $excludedMenuItems))
 			{
@@ -373,7 +364,7 @@ private function isExcluded(): bool
 		// If any pagecache plugins return true for onPageCacheIsExcluded, exclude.
 		PluginHelper::importPlugin('pagecache');
 
-		$results = $this->app->triggerEvent('onPageCacheIsExcluded');
+		$results = $this->getApplication()->triggerEvent('onPageCacheIsExcluded');
 
 		return in_array(true, $results, true);
 	}
@@ -395,6 +386,6 @@ public function onAfterRespond(Event $event)
 		}
 
 		// Saves current page in cache.
-		$this->getCacheController()->store($this->app->getBody(), $this->getCacheKey());
+		$this->getCacheController()->store($this->getApplication()->getBody(), $this->getCacheKey());
 	}
 }
diff --git a/plugins/task/requests/services/provider.php b/plugins/task/requests/services/provider.php
index f6600db7c022d..b7320429f62bc 100644
--- a/plugins/task/requests/services/provider.php
+++ b/plugins/task/requests/services/provider.php
@@ -10,6 +10,7 @@
 defined('_JEXEC') or die;
 
 use Joomla\CMS\Extension\PluginInterface;
+use Joomla\CMS\Factory;
 use Joomla\CMS\Plugin\PluginHelper;
 use Joomla\DI\Container;
 use Joomla\DI\ServiceProviderInterface;
@@ -37,8 +38,10 @@ function (Container $container)
 				$plugin = new Requests(
 					$container->get(DispatcherInterface::class),
 					(array) PluginHelper::getPlugin('task', 'requests'),
-					new HttpFactory
+					new HttpFactory,
+					JPATH_ROOT . '/tmp'
 				);
+				$plugin->setApplication(Factory::getApplication());
 
 				return $plugin;
 			}
diff --git a/plugins/task/requests/src/Extension/Requests.php b/plugins/task/requests/src/Extension/Requests.php
index 98fe7f53ab3cf..96cac4e98a7a4 100644
--- a/plugins/task/requests/src/Extension/Requests.php
+++ b/plugins/task/requests/src/Extension/Requests.php
@@ -29,7 +29,7 @@
  *
  * @since  4.1.0
  */
-class Requests extends CMSPlugin implements SubscriberInterface
+final class Requests extends CMSPlugin implements SubscriberInterface
 {
 	use TaskPluginTrait;
 
@@ -68,35 +68,37 @@ public static function getSubscribedEvents(): array
 	protected $autoloadLanguage = true;
 
 	/**
-	 * The application object
+	 * The http factory
 	 *
-	 * @var    CMSApplicationInterface
+	 * @var    HttpFactory
 	 * @since  __DEPLOY_VERSION__
 	 */
-	protected $app;
+	private $httpFactory;
 
 	/**
-	 * The http factory
+	 * The root directory
 	 *
-	 * @var    HttpFactory
+	 * @var    string
 	 * @since  __DEPLOY_VERSION__
 	 */
-	private $httpFactory;
+	private $rootDirectory;
 
 	/**
 	 * Constructor.
 	 *
-	 * @param   DispatcherInterface  $dispatcher   The dispatcher
-	 * @param   array                $config       An optional associative array of configuration settings
-	 * @param   HttpFactory          $httpFactory  The http factory
+	 * @param   DispatcherInterface  $dispatcher     The dispatcher
+	 * @param   array                $config         An optional associative array of configuration settings
+	 * @param   HttpFactory          $httpFactory    The http factory
+	 * @param   string               $rootDirectory  The root directory to store the output file in
 	 *
 	 * @since   __DEPLOY_VERSION__
 	 */
-	public function __construct(DispatcherInterface $dispatcher, array $config, HttpFactory $httpFactory)
+	public function __construct(DispatcherInterface $dispatcher, array $config, HttpFactory $httpFactory, string $rootDirectory)
 	{
 		parent::__construct($dispatcher, $config);
 
-		$this->httpFactory = $httpFactory;
+		$this->httpFactory   = $httpFactory;
+		$this->rootDirectory = $rootDirectory;
 	}
 
 	/**
@@ -132,7 +134,7 @@ protected function makeGetRequest(ExecuteTaskEvent $event): int
 		}
 		catch (Exception $e)
 		{
-			$this->logTask($this->app->getLanguage()->_('PLG_TASK_REQUESTS_TASK_GET_REQUEST_LOG_TIMEOUT'));
+			$this->logTask($this->translate('PLG_TASK_REQUESTS_TASK_GET_REQUEST_LOG_TIMEOUT'));
 
 			return TaskStatus::TIMEOUT;
 		}
@@ -141,16 +143,17 @@ protected function makeGetRequest(ExecuteTaskEvent $event): int
 		$responseBody = $response->body;
 
 		// @todo this handling must be rethought and made safe. stands as a good demo right now.
-		$responseFilename = Path::clean(JPATH_ROOT . "/tmp/task_{$id}_response.html");
+		$responseFilename = Path::clean($this->rootDirectory . "/task_{$id}_response.html");
 
-		if (File::write($responseFilename, $responseBody))
+		try
 		{
+			File::write($responseFilename, $responseBody);
 			$this->snapshot['output_file'] = $responseFilename;
 			$responseStatus = 'SAVED';
 		}
-		else
+		catch (Exception $e)
 		{
-			$this->logTask($this->app->getLanguage()->_('PLG_TASK_REQUESTS_TASK_GET_REQUEST_LOG_UNWRITEABLE_OUTPUT'), 'error');
+			$this->logTask($this->translate('PLG_TASK_REQUESTS_TASK_GET_REQUEST_LOG_UNWRITEABLE_OUTPUT'), 'error');
 			$responseStatus = 'NOT_SAVED';
 		}
 
@@ -161,7 +164,7 @@ protected function makeGetRequest(ExecuteTaskEvent $event): int
 > Response: $responseStatus
 EOF;
 
-		$this->logTask(sprintf($this->app->getLanguage()->_('PLG_TASK_REQUESTS_TASK_GET_REQUEST_LOG_RESPONSE'), $responseCode));
+		$this->logTask($this->translate('PLG_TASK_REQUESTS_TASK_GET_REQUEST_LOG_RESPONSE', $responseCode));
 
 		if ($response->code !== 200)
 		{
diff --git a/tests/Unit/Libraries/Cms/Plugin/CMSPluginTest.php b/tests/Unit/Libraries/Cms/Plugin/CMSPluginTest.php
new file mode 100644
index 0000000000000..32c35f23c0642
--- /dev/null
+++ b/tests/Unit/Libraries/Cms/Plugin/CMSPluginTest.php
@@ -0,0 +1,533 @@
+<?php
+/**
+ * @package     Joomla.UnitTest
+ * @subpackage  Base
+ *
+ * @copyright   (C) 2022 Open Source Matters, Inc. <https://www.joomla.org>
+ * @license     GNU General Public License version 2 or later; see LICENSE.txt
+ */
+
+namespace Joomla\Tests\Unit\Libraries\Cms\Plugin;
+
+use Joomla\CMS\Application\CMSApplicationInterface;
+use Joomla\CMS\Language\Language;
+use Joomla\CMS\Plugin\CMSPlugin;
+use Joomla\Event\Dispatcher;
+use Joomla\Event\Event;
+use Joomla\Event\EventInterface;
+use Joomla\Event\SubscriberInterface;
+use Joomla\Registry\Registry;
+use Joomla\Tests\Unit\UnitTestCase;
+use stdClass;
+
+/**
+ * Test class for \Joomla\CMS\Plugin\CMSPlugin
+ *
+ * @package     Joomla.UnitTest
+ * @subpackage  Plugin
+ *
+ * @testdox     The CMSPlugin
+ *
+ * @since       __DEPLOY_VERSION__
+ */
+class CMSPluginTest extends UnitTestCase
+{
+	/**
+	 * @testdox  has the correct dispatcher
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function testInjectedDispatcher()
+	{
+		$dispatcher = new Dispatcher;
+
+		$plugin = new class($dispatcher, []) extends CMSPlugin
+		{};
+
+		$this->assertEquals($dispatcher, $plugin->getDispatcher());
+	}
+
+	/**
+	 * @testdox  has the correct dispatcher
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function testInjectedApplication()
+	{
+		$dispatcher = new Dispatcher;
+		$app        = $this->createStub(CMSApplicationInterface::class);
+
+		$plugin = new class($dispatcher, []) extends CMSPlugin
+		{
+			public function getApplication(): CMSApplicationInterface
+			{
+				return parent::getApplication();
+			}
+		};
+		$plugin->setApplication($app);
+
+		$this->assertEquals($app, $plugin->getApplication());
+	}
+
+	/**
+	 * @testdox  has null params when not set
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function testEmptyParams()
+	{
+		$dispatcher = new Dispatcher;
+
+		$plugin = new class($dispatcher, []) extends CMSPlugin
+		{};
+
+		$this->assertNull($plugin->params);
+	}
+
+	/**
+	 * @testdox  gets the injected params from a registry object
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function testInjectedRegistryParams()
+	{
+		$dispatcher = new Dispatcher;
+		$registry   = new Registry;
+
+		$plugin = new class($dispatcher, ['params' => $registry]) extends CMSPlugin
+		{};
+
+		$this->assertEquals($registry, $plugin->params);
+	}
+
+	/**
+	 * @testdox  gets the injected params from array
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function testInjectedArrayParams()
+	{
+		$dispatcher = new Dispatcher;
+
+		$plugin = new class($dispatcher, ['params' => ['test' => 'unit']]) extends CMSPlugin
+		{};
+
+		$this->assertEquals('unit', $plugin->params->get('test'));
+	}
+
+	/**
+	 * @testdox  gets the injected name
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function testInjectedName()
+	{
+		$dispatcher = new Dispatcher;
+
+		$plugin = new class($dispatcher, ['name' => 'test']) extends CMSPlugin
+		{
+			public function getName()
+			{
+				return $this->_name;
+			}
+		};
+
+		$this->assertEquals('test', $plugin->getName());
+	}
+
+	/**
+	 * @testdox  gets the injected type
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function testInjectedType()
+	{
+		$dispatcher = new Dispatcher;
+
+		$plugin = new class($dispatcher, ['type' => 'test']) extends CMSPlugin
+		{
+			public function getType()
+			{
+				return $this->_type;
+			}
+		};
+
+		$this->assertEquals('test', $plugin->getType());
+	}
+
+	/**
+	 * @testdox  can load the language
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function testLoadLanguage()
+	{
+		$dispatcher = new Dispatcher;
+		$language = $this->createMock(Language::class);
+		$language->expects($this->once())->method('load')->with($this->equalTo('plg__'), JPATH_ADMINISTRATOR)->willReturn(true);
+
+		$app = $this->createStub(CMSApplicationInterface::class);
+		$app->method('getLanguage')->willReturn($language);
+
+		$plugin = new class($dispatcher, []) extends CMSPlugin
+		{};
+		$plugin->setApplication($app);
+		$plugin->loadLanguage();
+	}
+
+	/**
+	 * @testdox  can load the language for a custom extension and path
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function testLoadLanguageWithExtensionAndPath()
+	{
+		$dispatcher = new Dispatcher;
+		$language = $this->createMock(Language::class);
+		$language->expects($this->once())->method('load')->with($this->equalTo('test'), __DIR__)->willReturn(true);
+
+		$app = $this->createStub(CMSApplicationInterface::class);
+		$app->method('getLanguage')->willReturn($language);
+
+		$plugin = new class($dispatcher, []) extends CMSPlugin
+		{};
+		$plugin->setApplication($app);
+		$plugin->loadLanguage('test', __DIR__);
+	}
+
+	/**
+	 * @testdox  does not load the language when the path exists
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function testNotLoadLanguageWhenExists()
+	{
+		$dispatcher = new Dispatcher;
+		$language = $this->createMock(Language::class);
+		$language->method('getPaths')->willReturn(true);
+		$language->expects($this->never())->method('load');
+
+		$app = $this->createStub(CMSApplicationInterface::class);
+		$app->method('getLanguage')->willReturn($language);
+
+		$plugin = new class($dispatcher, []) extends CMSPlugin
+		{};
+		$plugin->setApplication($app);
+		$plugin->loadLanguage();
+	}
+
+	/**
+	 * @testdox  can translate a string without arguments
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function testTranslateWithoutArguments()
+	{
+		$dispatcher = new Dispatcher;
+		$language = $this->createMock(Language::class);
+		$language->method('_')->willReturn('test');
+
+		$app = $this->createStub(CMSApplicationInterface::class);
+		$app->method('getLanguage')->willReturn($language);
+
+		$plugin = new class($dispatcher, []) extends CMSPlugin
+		{
+			public function test(): string
+			{
+				return parent::translate('unit');
+			}
+		};
+		$plugin->setApplication($app);
+
+		$this->assertEquals('test', $plugin->test());
+	}
+
+	/**
+	 * @testdox  can translate a string with arguments
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function testTranslateWithArguments()
+	{
+		$dispatcher = new Dispatcher;
+		$language = $this->createMock(Language::class);
+		$language->method('_')->willReturn('test %s in %s');
+
+		$app = $this->createStub(CMSApplicationInterface::class);
+		$app->method('getLanguage')->willReturn($language);
+
+		$plugin = new class($dispatcher, []) extends CMSPlugin
+		{
+			public function test(): string
+			{
+				return parent::translate('unit', 1, 'two');
+			}
+		};
+		$plugin->setApplication($app);
+
+		$this->assertEquals('test 1 in two', $plugin->test());
+	}
+
+	/**
+	 * @testdox  can register the listeners when is SubscriberInterface
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function testRegisterListenersAsSubscriber()
+	{
+		$dispatcher = new Dispatcher;
+
+		$plugin = new class($dispatcher, []) extends CMSPlugin implements SubscriberInterface
+		{
+			public static function getSubscribedEvents(): array
+			{
+				return ['test' => 'unit'];
+			}
+
+			public function unit()
+			{}
+		};
+		$plugin->registerListeners();
+
+		$this->assertEquals([[$plugin, 'unit']], $dispatcher->getListeners('test'));
+	}
+
+	/**
+	 * @testdox  can register the listeners when is legacy
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function testRegisterListenersAsLegacy()
+	{
+		$dispatcher = new Dispatcher;
+
+		$plugin = new class($dispatcher, []) extends CMSPlugin
+		{
+			public function onTest()
+			{}
+		};
+		$plugin->registerListeners();
+
+		$this->assertCount(1, $dispatcher->getListeners('onTest'));
+	}
+
+	/**
+	 * @testdox  can register the listeners with event interface
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function testRegisterListenersForEventInterface()
+	{
+		$dispatcher = new Dispatcher;
+
+		$plugin = new class($dispatcher, []) extends CMSPlugin
+		{
+			public function onTest(EventInterface $event)
+			{}
+		};
+		$plugin->registerListeners();
+
+		$this->assertCount(1, $dispatcher->getListeners('onTest'));
+	}
+
+	/**
+	 * @testdox  must register the listeners with event interface
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function testRegisterListenersWithForcedEventInterface()
+	{
+		$dispatcher = new Dispatcher;
+
+		$plugin = new class($dispatcher, []) extends CMSPlugin
+		{
+			protected $allowLegacyListeners = false;
+
+			public function onTest(EventInterface $event)
+			{}
+		};
+		$plugin->registerListeners();
+
+		$this->assertCount(1, $dispatcher->getListeners('onTest'));
+	}
+
+	/**
+	 * @testdox  can register the listeners when has typed arguments
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function testRegisterListenersForNoEventInterface()
+	{
+		$dispatcher = new Dispatcher;
+
+		$plugin = new class($dispatcher, []) extends CMSPlugin
+		{
+			public function onTest(string $context)
+			{}
+		};
+		$plugin->registerListeners();
+
+		$this->assertCount(1, $dispatcher->getListeners('onTest'));
+	}
+
+	/**
+	 * @testdox  can register the listeners when has untyped arguments
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function testRegisterListenersNotTyped()
+	{
+		$dispatcher = new Dispatcher;
+
+		$plugin = new class($dispatcher, []) extends CMSPlugin
+		{
+			public function onTest($event)
+			{}
+		};
+		$plugin->registerListeners();
+
+		$this->assertCount(1, $dispatcher->getListeners('onTest'));
+	}
+
+	/**
+	 * @testdox  can register the listeners when has nullable arguments
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function testRegisterListenersNullable()
+	{
+		$dispatcher = new Dispatcher;
+
+		$plugin = new class($dispatcher, []) extends CMSPlugin
+		{
+			public function onTest(stdClass $event = null)
+			{}
+		};
+		$plugin->registerListeners();
+
+		$this->assertCount(1, $dispatcher->getListeners('onTest'));
+	}
+
+	/**
+	 * @testdox  can dispatch a legacy listener
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function testDispatchLegacyListener()
+	{
+		$dispatcher = new Dispatcher;
+
+		$plugin = new class($dispatcher, []) extends CMSPlugin
+		{
+			public function registerTestListener()
+	    	{
+	        	parent::registerLegacyListener('onTest');
+	    	}
+
+			public function onTest()
+			{
+				return 'unit';
+			}
+		};
+		$plugin->registerTestListener();
+		$event = $dispatcher->dispatch('onTest');
+
+		$this->assertEquals(['unit'], $event->getArgument('result'));
+	}
+
+	/**
+	 * @testdox  can dispatch a legacy listener with null result
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function testDispatchLegacyListenerWhenNullIsReturned()
+	{
+		$dispatcher = new Dispatcher;
+
+		$plugin = new class($dispatcher, []) extends CMSPlugin
+		{
+			public function registerTestListener()
+	    	{
+	        	parent::registerLegacyListener('onTest');
+	    	}
+
+			public function onTest()
+			{}
+		};
+		$plugin->registerTestListener();
+		$event = $dispatcher->dispatch('onTest');
+
+		$this->assertEquals(null, $event->getArgument('result'));
+	}
+
+	/**
+	 * @testdox  can dispatch a legacy listener and contains the result from the event and the plugin
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function testDispatchLegacyListenerWhenEventHasResult()
+	{
+		$dispatcher = new Dispatcher;
+
+		$plugin = new class($dispatcher, []) extends CMSPlugin
+		{
+			public function registerTestListener()
+			{
+				parent::registerLegacyListener('onTest');
+			}
+
+			public function onTest()
+			{
+				return 'unit';
+			}
+		};
+		$plugin->registerTestListener();
+		$event = $dispatcher->dispatch('onTest', new Event('onTest', ['result' => ['test']]));
+
+		$this->assertEquals(['test', 'unit'], $event->getArgument('result'));
+	}
+}
diff --git a/tests/Unit/Plugin/Task/Requests/Extension/RequestsPluginTest.php b/tests/Unit/Plugin/Task/Requests/Extension/RequestsPluginTest.php
new file mode 100644
index 0000000000000..ced18b36249d3
--- /dev/null
+++ b/tests/Unit/Plugin/Task/Requests/Extension/RequestsPluginTest.php
@@ -0,0 +1,327 @@
+<?php
+/**
+ * @package     Joomla.UnitTest
+ * @subpackage  Extension
+ *
+ * @copyright   (C) 2022 Open Source Matters, Inc. <https://www.joomla.org>
+ * @license     GNU General Public License version 2 or later; see LICENSE.txt
+ */
+
+namespace Joomla\Tests\Unit\Plugin\Task\Requests\Extension;
+
+use Exception;
+use Joomla\CMS\Application\CMSApplicationInterface;
+use Joomla\CMS\Http\Http;
+use Joomla\CMS\Language\Language;
+use Joomla\Component\Scheduler\Administrator\Event\ExecuteTaskEvent;
+use Joomla\Component\Scheduler\Administrator\Task\Status;
+use Joomla\Component\Scheduler\Administrator\Task\Task;
+use Joomla\Event\Dispatcher;
+use Joomla\Filesystem\Folder;
+use Joomla\Http\HttpFactory;
+use Joomla\Http\TransportInterface;
+use Joomla\Plugin\Task\Requests\Extension\Requests;
+use Joomla\Tests\Unit\UnitTestCase;
+use Joomla\Uri\UriInterface;
+
+/**
+ * Test class for Requests plugin
+ *
+ * @package     Joomla.UnitTest
+ * @subpackage  Requests
+ *
+ * @testdox     The Requests plugin
+ *
+ * @since       __DEPLOY_VERSION__
+ */
+class RequestsPluginTest extends UnitTestCase
+{
+	/**
+	 * Setup
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function setUp(): void
+    {
+		if (is_dir(__DIR__ . '/tmp'))
+		{
+			Folder::delete(__DIR__ . '/tmp');
+		}
+    }
+
+	/**
+	 * Cleanup
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function tearDown(): void
+    {
+		if (is_dir(__DIR__ . '/tmp'))
+		{
+			Folder::delete(__DIR__ . '/tmp');
+		}
+    }
+
+	/**
+	 * @testdox  can perform a HTTP GET request
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function testRequest()
+	{
+		$transport = new class implements TransportInterface
+		{
+			public $url;
+
+			public function request($method, UriInterface $uri, $data = null, array $headers = [], $timeout = null, $userAgent = null)
+			{
+				$this->url = $uri->toString();
+
+				return (object)['code' => 200, 'body' => 'test'];
+			}
+
+			public static function isSupported()
+			{
+				return true;
+			}
+		};
+
+		$http = new Http([], $transport);
+		$factory = $this->createStub(HttpFactory::class);
+		$factory->method('getHttp')->willReturn($http);
+
+		$app = $this->createStub(CMSApplicationInterface::class);
+		$app->method('getLanguage')->willReturn($this->createStub(Language::class));
+
+		$plugin = new Requests(new Dispatcher, [], $factory, __DIR__ . '/tmp');
+		$plugin->setApplication($app);
+
+		$task = $this->createStub(Task::class);
+		$task->method('get')->willReturnMap([['id', null, 1], ['type', null, 'plg_task_requests_task_get']]);
+
+		$event = new ExecuteTaskEvent(
+			'test',
+			[
+				'subject' => $task,
+				'params' => (object)['url' => 'http://example.com', 'timeout' => 0, 'auth' => 0, 'authType' => '', 'authKey' => '']
+			]
+		);
+		$plugin->standardRoutineHandler($event);
+
+		$this->assertEquals(Status::OK, $event->getResultSnapshot()['status']);
+		$this->assertStringContainsString('SAVED', $event->getResultSnapshot()['output']);
+		$this->assertEquals('http://example.com', $transport->url);
+		$this->assertStringEqualsFile(__DIR__ . '/tmp/task_1_response.html', 'test');
+	}
+
+	/**
+	 * @testdox  can perform a HTTP GET request where the return code is not 200
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function testInvalidRequest()
+	{
+		$transport = new class implements TransportInterface
+		{
+			public $url;
+
+			public function request($method, UriInterface $uri, $data = null, array $headers = [], $timeout = null, $userAgent = null)
+			{
+				$this->url = $uri->toString();
+
+				return (object)['code' => 404, 'body' => 'test'];
+			}
+
+			public static function isSupported()
+			{
+				return true;
+			}
+		};
+
+		$http = new Http([], $transport);
+		$factory = $this->createStub(HttpFactory::class);
+		$factory->method('getHttp')->willReturn($http);
+
+		$app = $this->createStub(CMSApplicationInterface::class);
+		$app->method('getLanguage')->willReturn($this->createStub(Language::class));
+
+		$plugin = new Requests(new Dispatcher, [], $factory, __DIR__ . '/tmp');
+		$plugin->setApplication($app);
+
+		$task = $this->createStub(Task::class);
+		$task->method('get')->willReturnMap([['id', null, 1], ['type', null, 'plg_task_requests_task_get']]);
+
+		$event = new ExecuteTaskEvent(
+			'test',
+			[
+				'subject' => $task,
+				'params' => (object)['url' => 'http://example.com', 'timeout' => 0, 'auth' => 0, 'authType' => '', 'authKey' => '']
+			]
+		);
+		$plugin->standardRoutineHandler($event);
+
+		$this->assertEquals(Status::KNOCKOUT, $event->getResultSnapshot()['status']);
+		$this->assertStringContainsString('SAVED', $event->getResultSnapshot()['output']);
+		$this->assertEquals('http://example.com', $transport->url);
+		$this->assertStringEqualsFile(__DIR__ . '/tmp/task_1_response.html', 'test');
+	}
+
+	/**
+	 * @testdox  can perform a HTTP GET request with auth headers
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function testAuthRequest()
+	{
+		$transport = new class implements TransportInterface
+		{
+			public $headers;
+
+			public function request($method, UriInterface $uri, $data = null, array $headers = [], $timeout = null, $userAgent = null)
+			{
+				$this->headers = $headers;
+
+				return (object)['code' => 200, 'body' => 'test'];
+			}
+
+			public static function isSupported()
+			{
+				return true;
+			}
+		};
+
+		$http = new Http([], $transport);
+		$factory = $this->createStub(HttpFactory::class);
+		$factory->method('getHttp')->willReturn($http);
+
+		$app = $this->createStub(CMSApplicationInterface::class);
+		$app->method('getLanguage')->willReturn($this->createStub(Language::class));
+
+		$plugin = new Requests(new Dispatcher, [], $factory, __DIR__ . '/tmp');
+		$plugin->setApplication($app);
+
+		$task = $this->createStub(Task::class);
+		$task->method('get')->willReturnMap([['id', null, 1], ['type', null, 'plg_task_requests_task_get']]);
+
+		$event = new ExecuteTaskEvent(
+			'test',
+			[
+				'subject' => $task,
+				'params' => (object)['url' => 'http://example.com', 'timeout' => 0, 'auth' => 1, 'authType' => 'basic', 'authKey' => '123']
+			]
+		);
+		$plugin->standardRoutineHandler($event);
+
+		$this->assertEquals(['basic' => '123'], $transport->headers);
+	}
+
+	/**
+	 * @testdox  can handle an exception during the request
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function testExceptionInRequest()
+	{
+		$transport = new class implements TransportInterface
+		{
+			public function request($method, UriInterface $uri, $data = null, array $headers = [], $timeout = null, $userAgent = null)
+			{
+				throw new Exception('test');
+			}
+
+			public static function isSupported()
+			{
+				return true;
+			}
+		};
+
+		$http = new Http([], $transport);
+		$factory = $this->createStub(HttpFactory::class);
+		$factory->method('getHttp')->willReturn($http);
+
+		$language = $this->createStub(Language::class);
+		$language->method('_')->willReturn('test');
+
+		$app = $this->createStub(CMSApplicationInterface::class);
+		$app->method('getLanguage')->willReturn($language);
+
+		$plugin = new Requests(new Dispatcher, [], $factory, __DIR__ . '/tmp');
+		$plugin->setApplication($app);
+
+		$task = $this->createStub(Task::class);
+		$task->method('get')->willReturnMap([['id', null, 1], ['type', null, 'plg_task_requests_task_get']]);
+
+		$event = new ExecuteTaskEvent(
+			'test',
+			[
+				'subject' => $task,
+				'params' => (object)['url' => 'http://example.com', 'timeout' => 0, 'auth' => 0, 'authType' => '', 'authKey' => '']
+			]
+		);
+		$plugin->standardRoutineHandler($event);
+
+		$this->assertEquals(Status::TIMEOUT, $event->getResultSnapshot()['status']);
+	}
+	/**
+	 * @testdox  can handle an invalid file location
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function testInvalidFileToWrite()
+	{
+		$transport = new class implements TransportInterface
+		{
+			public function request($method, UriInterface $uri, $data = null, array $headers = [], $timeout = null, $userAgent = null)
+			{
+				return (object)['code' => 200, 'body' => 'test'];
+			}
+
+			public static function isSupported()
+			{
+				return true;
+			}
+		};
+
+		$http = new Http([], $transport);
+		$factory = $this->createStub(HttpFactory::class);
+		$factory->method('getHttp')->willReturn($http);
+
+		$language = $this->createStub(Language::class);
+		$language->method('_')->willReturn('test');
+
+		$app = $this->createStub(CMSApplicationInterface::class);
+		$app->method('getLanguage')->willReturn($language);
+
+		$plugin = new Requests(new Dispatcher, [], $factory, '/invalid');
+		$plugin->setApplication($app);
+
+		$task = $this->createStub(Task::class);
+		$task->method('get')->willReturnMap([['id', null, 1], ['type', null, 'plg_task_requests_task_get']]);
+
+		$event = new ExecuteTaskEvent(
+			'test',
+			[
+				'subject' => $task,
+				'params' => (object)['url' => 'http://example.com', 'timeout' => 0, 'auth' => 0, 'authType' => '', 'authKey' => '']
+			]
+		);
+		$plugin->standardRoutineHandler($event);
+
+		$this->assertEquals(Status::OK, $event->getResultSnapshot()['status']);
+		$this->assertStringContainsString('NOT_SAVED', $event->getResultSnapshot()['output']);
+	}
+}