diff --git a/administrator/components/com_admin/script.php b/administrator/components/com_admin/script.php
index 105a9bbe85324..bcb4004487690 100644
--- a/administrator/components/com_admin/script.php
+++ b/administrator/components/com_admin/script.php
@@ -296,6 +296,12 @@ protected function uninstallRepeatableFieldsPlugin()
 				 */
 				$mapping = [];
 
+				/**
+				 * Store name of media fields which we need to convert data from old format (string) to new
+				 * format (json) during the migration
+				 */
+				$mediaFields = [];
+
 				// If this repeatable fields actually had child-fields (normally this is always the case)
 				if (isset($oldFieldparams->fields) && is_object($oldFieldparams->fields))
 				{
@@ -342,6 +348,11 @@ protected function uninstallRepeatableFieldsPlugin()
 								$data['type'] = 'text';
 							}
 
+							if ($data['type'] == 'media')
+							{
+								$mediaFields[] = $oldField->fieldname;
+							}
+
 							// Reset the state because else \Joomla\CMS\MVC\Model\AdminModel will take an already
 							// existing value (e.g. from previous save) and do an UPDATE instead of INSERT.
 							$fieldModel->setState('field.id', 0);
@@ -402,7 +413,7 @@ protected function uninstallRepeatableFieldsPlugin()
 				$db->setQuery(
 					$db->getQuery(true)
 						->update('#__fields')
-						->set($db->quoteName('type') . ' = ' . $db->quote('subfields'))
+						->set($db->quoteName('type') . ' = ' . $db->quote('subform'))
 						->set($db->quoteName('fieldparams') . ' = ' . $db->quote(json_encode($newFieldparams)))
 						->where($db->quoteName('id') . ' = ' . $db->quote($row->id))
 				)->execute();
@@ -440,13 +451,21 @@ protected function uninstallRepeatableFieldsPlugin()
 						continue;
 					}
 
+					$rowIndex = 0;
+
 					foreach ($fieldValue as $rowKey => $rowValue)
 					{
-						$rowKey                 = str_replace('repeatable', 'row', $rowKey);
+						$rowKey                 = 'row' . ($rowIndex++);
 						$newFieldValue[$rowKey] = [];
 
 						foreach ($rowValue as $subFieldName => $subFieldValue)
 						{
+							// This is a media field, so we need to convert data to new format required in Joomla! 4
+							if (in_array($subFieldName, $mediaFields))
+							{
+								$subFieldValue = ['imagefile' => $subFieldValue, 'alt_text' => ''];
+							}
+
 							if (isset($mapping[$subFieldName]))
 							{
 								$newFieldValue[$rowKey][$mapping[$subFieldName]] = $subFieldValue;