diff --git a/libraries/joomla/form/fields/checkbox.php b/libraries/joomla/form/fields/checkbox.php
index a7f3f04240f01..c2826f15890b5 100644
--- a/libraries/joomla/form/fields/checkbox.php
+++ b/libraries/joomla/form/fields/checkbox.php
@@ -36,6 +36,14 @@ class JFormFieldCheckbox extends JFormField
 	 */
 	protected $checked = false;
 
+	/**
+	 * Checkbox field should always have any value.
+	 *
+	 * @var    boolean
+	 * @since  __DEPLOY_VERSION__
+	 */
+	public $ensureValue = true;
+
 	/**
 	 * Method to get certain otherwise inaccessible properties from the form field object.
 	 *
diff --git a/libraries/joomla/form/fields/checkboxes.php b/libraries/joomla/form/fields/checkboxes.php
index 5b3c782bc791e..b5abe655670c2 100644
--- a/libraries/joomla/form/fields/checkboxes.php
+++ b/libraries/joomla/form/fields/checkboxes.php
@@ -46,13 +46,21 @@ class JFormFieldCheckboxes extends JFormFieldList
 	protected $forceMultiple = true;
 
 	/**
-	 * The comma seprated list of checked checkboxes value.
+	 * The comma separated list of checked checkboxes value.
 	 *
 	 * @var    mixed
 	 * @since  3.2
 	 */
 	public $checkedOptions;
 
+	/**
+	 * Checkboxes field should always have any value.
+	 *
+	 * @var    boolean
+	 * @since  __DEPLOY_VERSION__
+	 */
+	public $ensureValue = true;
+
 	/**
 	 * Method to get certain otherwise inaccessible properties from the form field object.
 	 *
diff --git a/libraries/src/Form/Form.php b/libraries/src/Form/Form.php
index 700cf67387595..8abd4588c91b9 100644
--- a/libraries/src/Form/Form.php
+++ b/libraries/src/Form/Form.php
@@ -186,14 +186,15 @@ protected function bindLevel($group, $data)
 	/**
 	 * Method to filter the form data.
 	 *
-	 * @param   array   $data   An array of field values to filter.
-	 * @param   string  $group  The dot-separated form group path on which to filter the fields.
+	 * @param   array   $data          An array of field values to filter.
+	 * @param   string  $group         The dot-separated form group path on which to filter the fields.
+	 * @param   bool    $ensureValues  Auto-inject empty values for fields which are supposed to always have values.
 	 *
 	 * @return  mixed  Array or false.
 	 *
 	 * @since   11.1
 	 */
-	public function filter($data, $group = null)
+	public function filter($data, $group = null, $ensureValues = true)
 	{
 		// Make sure there is a valid JForm XML document.
 		if (!($this->xml instanceof \SimpleXMLElement))
@@ -230,6 +231,11 @@ public function filter($data, $group = null)
 			{
 				$output->set($key, $this->filterField($field, $input->get($key, (string) $field['default'])));
 			}
+			// Auto-inject values.
+			elseif ($ensureValues && ($fieldInstance = $this->getField($name, $group)) && !empty($fieldInstance->ensureValue))
+			{
+				$output->set($key, null);
+			}
 		}
 
 		return $output->toArray();
diff --git a/plugins/system/fields/fields.php b/plugins/system/fields/fields.php
index 23afd468bd8e0..b815b78cad483 100644
--- a/plugins/system/fields/fields.php
+++ b/plugins/system/fields/fields.php
@@ -44,8 +44,8 @@ class PlgSystemFields extends JPlugin
 	 */
 	public function onContentAfterSave($context, $item, $isNew, $data = array())
 	{
-		// Check if data is an array and the item has an id
-		if (!is_array($data) || empty($item->id))
+		// Check if data is an array and the item has an id and we have custom fields data
+		if (!is_array($data) || empty($item->id) || empty($data['com_fields']))
 		{
 			return true;
 		}
@@ -78,26 +78,25 @@ public function onContentAfterSave($context, $item, $isNew, $data = array())
 			return true;
 		}
 
-		// Get the fields data
-		$fieldsData = !empty($data['com_fields']) ? $data['com_fields'] : array();
-
 		// Loading the model
 		$model = JModelLegacy::getInstance('Field', 'FieldsModel', array('ignore_request' => true));
 
 		// Loop over the fields
 		foreach ($fields as $field)
 		{
-			// Determine the value if it is available from the data
-			$value = key_exists($field->name, $fieldsData) ? $fieldsData[$field->name] : null;
-
-			// JSON encode value for complex fields
-			if (is_array($value) && (count($value, COUNT_NORMAL) !== count($value, COUNT_RECURSIVE) || !count(array_filter(array_keys($value), 'is_numeric'))))
+			// Update field value if we have it.
+			if (array_key_exists($field->name, $data['com_fields']))
 			{
-				$value = json_encode($value);
-			}
+				$value = $data['com_fields'][$field->name];
+
+				// JSON encode value for complex fields
+				if (is_array($value) && count($value, COUNT_NORMAL) !== count($value, COUNT_RECURSIVE))
+				{
+					$value = json_encode($value);
+				}
 
-			// Setting the value for the field and the item
-			$model->setFieldValue($field->id, $item->id, $value);
+				$model->setFieldValue($field->id, $item->id, $value);
+			}
 		}
 
 		return true;
@@ -126,14 +125,6 @@ public function onUserAfterSave($userData, $isNew, $success, $msg)
 
 		$user = JFactory::getUser($userData['id']);
 
-		$task = JFactory::getApplication()->input->getCmd('task');
-
-		// Skip fields save when we activate a user, because we will lose the saved data
-		if (in_array($task, array('activate', 'block', 'unblock')))
-		{
-			return true;
-		}
-
 		// Trigger the events with a real user
 		$this->onContentAfterSave('com_users.user', $user, false, $userData);