diff --git a/typo3/sysext/extbase/Classes/Configuration/AbstractConfigurationManager.php b/typo3/sysext/extbase/Classes/Configuration/AbstractConfigurationManager.php
index 01a91bea9bf9..d729231d88a6 100644
--- a/typo3/sysext/extbase/Classes/Configuration/AbstractConfigurationManager.php
+++ b/typo3/sysext/extbase/Classes/Configuration/AbstractConfigurationManager.php
@@ -222,18 +222,88 @@ public function getDefaultBackendStoragePid()
     }
 
     /**
+     * This method possibly overrides the controller configuration with an alternative configuration passed along via
+     * $frameworkConfiguration.
+     *
+     * If called by \TYPO3\CMS\Extbase\Configuration\AbstractConfigurationManager::getConfiguration,
+     * $switchableControllerActions may contain an alternative controller configuration defined via typoscript:
+     *
+     * Example:
+     * tt_content.list.20.indexedsearch_pi2.switchableControllerActions {
+     *     Search {
+     *         0 = search
+     *     }
+     * }
+     *
+     * If called by \TYPO3\CMS\Extbase\Configuration\FrontendConfigurationManager::overrideSwitchableControllerActionsFromFlexForm,
+     * $switchableControllerActions may contain an alternative controller configuration defined via plugin flexform.
+     *
      * @param array &$frameworkConfiguration
      * @param array $switchableControllerActions
      */
     protected function overrideSwitchableControllerActions(array &$frameworkConfiguration, array $switchableControllerActions)
     {
+        $controllerAliasToClass = [];
+        foreach ($frameworkConfiguration['controllerConfiguration'] as $controllerClass => $controllerConfiguration) {
+            $controllerAliasToClass[$controllerConfiguration['alias']] = $controllerClass;
+        }
+
         $overriddenSwitchableControllerActions = [];
         foreach ($switchableControllerActions as $controllerName => $actions) {
-            if (!isset($frameworkConfiguration['controllerConfiguration'][$controllerName])) {
+            // Trim leading backslashes if a fully qualified controller class name with leading slashes is used.
+            $controllerName = ltrim($controllerName, '\\');
+
+            $controllerIsConfigured = false;
+            if (array_key_exists($controllerName, $controllerAliasToClass)) {
+                /*
+                 * If $controllerName can be found in the keys of $controllerAliasToClass, $controllerName is a
+                 * controller alias and not a FQCN. In this case switchable controller actions have been defined with
+                 * controller aliases as such:
+                 *
+                 * tt_content.list.20.indexedsearch_pi2.switchableControllerActions {
+                 *     Search {
+                 *         0 = search
+                 *     }
+                 * }
+                 */
+                $controllerIsConfigured = true;
+                $controllerClassName = $controllerAliasToClass[$controllerName];
+                $controllerAlias = $controllerName;
+            }
+
+            if (in_array($controllerName, $controllerAliasToClass, true)) {
+                /*
+                 * If $controllerName can be found in the values of $controllerAliasToClass, $controllerName is a
+                 * FQCN. In this case switchable controller actions have been defined with fully qualified controller
+                 * class names as such:
+                 *
+                 * tt_content.list.20.indexedsearch_pi2.switchableControllerActions {
+                 *     TYPO3\CMS\IndexedSearch\Controller\SearchController {
+                 *         0 = search
+                 *     }
+                 * }
+                 */
+                $controllerIsConfigured = true;
+                $controllerClassName = $controllerName;
+                $controllerAlias = $frameworkConfiguration['controllerConfiguration'][$controllerName]['alias'];
+            }
+
+            if (!$controllerIsConfigured) {
                 continue;
             }
-            $overriddenSwitchableControllerActions[$controllerName] = ['actions' => $actions];
-            $nonCacheableActions = $frameworkConfiguration['controllerConfiguration'][$controllerName]['nonCacheableActions'] ?? null;
+
+            if (!isset($overriddenSwitchableControllerActions[$controllerClassName])) {
+                $overriddenSwitchableControllerActions[$controllerClassName] = [
+                    'alias' => $controllerAlias,
+                    'className' => $controllerClassName,
+                    'actions' => []
+                ];
+            }
+            $overriddenSwitchableControllerActions[$controllerClassName]['actions'] = array_merge(
+                $overriddenSwitchableControllerActions[$controllerClassName]['actions'],
+                $actions
+            );
+            $nonCacheableActions = $frameworkConfiguration['controllerConfiguration'][$controllerClassName]['nonCacheableActions'] ?? null;
             if (!is_array($nonCacheableActions)) {
                 // There are no non-cacheable actions, thus we can directly continue
                 // with the next controller name.
@@ -241,7 +311,7 @@ protected function overrideSwitchableControllerActions(array &$frameworkConfigur
             }
             $overriddenNonCacheableActions = array_intersect($nonCacheableActions, $actions);
             if (!empty($overriddenNonCacheableActions)) {
-                $overriddenSwitchableControllerActions[$controllerName]['nonCacheableActions'] = $overriddenNonCacheableActions;
+                $overriddenSwitchableControllerActions[$controllerClassName]['nonCacheableActions'] = $overriddenNonCacheableActions;
             }
         }
         $frameworkConfiguration['controllerConfiguration'] = $overriddenSwitchableControllerActions;
diff --git a/typo3/sysext/extbase/Tests/Unit/Configuration/AbstractConfigurationManagerTest.php b/typo3/sysext/extbase/Tests/Unit/Configuration/AbstractConfigurationManagerTest.php
index 23ff0a3e38a7..833ece29d470 100644
--- a/typo3/sysext/extbase/Tests/Unit/Configuration/AbstractConfigurationManagerTest.php
+++ b/typo3/sysext/extbase/Tests/Unit/Configuration/AbstractConfigurationManagerTest.php
@@ -106,10 +106,12 @@ class AbstractConfigurationManagerTest extends UnitTestCase
      * @var array
      */
     protected $testSwitchableControllerActions = [
-        'Controller1' => [
+        'MyExtension\\Controller\\Controller1' => [
+            'alias' => 'Controller1',
             'actions' => ['action1', 'action2', 'action3']
         ],
-        'Controller2' => [
+        'MyExtension\\Controller\\Controller2' => [
+            'alias' => 'Controller2',
             'actions' => ['action4', 'action5', 'action6'],
             'nonCacheableActions' => ['action4', 'action6']
         ]
@@ -506,7 +508,9 @@ public function orderOfActionsCanBeOverriddenForCurrentPlugin(): void
         }));
         $mergedConfiguration = $this->abstractConfigurationManager->getConfiguration();
         $expectedResult = [
-            'Controller1' => [
+            'MyExtension\\Controller\\Controller1' => [
+                'className' => 'MyExtension\\Controller\\Controller1',
+                'alias' => 'Controller1',
                 'actions' => ['action2', 'action1', 'action3']
             ]
         ];
@@ -514,6 +518,52 @@ public function orderOfActionsCanBeOverriddenForCurrentPlugin(): void
         $this->assertEquals($expectedResult, $actualResult);
     }
 
+    /**
+     * @test
+     */
+    public function controllerOfSwitchableControllerActionsCanBeAFullyQualifiedClassName(): void
+    {
+        $configuration = [
+            'extensionName' => 'CurrentExtensionName',
+            'pluginName' => 'CurrentPluginName',
+            'switchableControllerActions' => [
+                'MyExtension\\Controller\\Controller1' => ['action2', 'action1', 'action3'],
+                '\\MyExtension\\Controller\\Controller2' => ['newAction2', 'action4', 'action5']
+            ]
+        ];
+        $this->mockTypoScriptService->expects($this->any())->method('convertTypoScriptArrayToPlainArray')->with($configuration)->will($this->returnValue($configuration));
+        $this->abstractConfigurationManager->setConfiguration($configuration);
+        $this->abstractConfigurationManager->expects($this->once())->method('getPluginConfiguration')->with(
+            'CurrentExtensionName',
+            'CurrentPluginName'
+        )->will($this->returnValue($this->testPluginConfiguration));
+        $this->abstractConfigurationManager->expects($this->once())->method('getSwitchableControllerActions')->with(
+            'CurrentExtensionName',
+            'CurrentPluginName'
+        )->will($this->returnValue($this->testSwitchableControllerActions));
+        $this->abstractConfigurationManager->expects($this->once())->method('getContextSpecificFrameworkConfiguration')->will($this->returnCallback(function (
+            $a
+        ) {
+            return $a;
+        }));
+        $mergedConfiguration = $this->abstractConfigurationManager->getConfiguration();
+        $expectedResult = [
+            'MyExtension\\Controller\\Controller1' => [
+                'className' => 'MyExtension\\Controller\\Controller1',
+                'alias' => 'Controller1',
+                'actions' => ['action2', 'action1', 'action3']
+            ],
+            'MyExtension\\Controller\\Controller2' => [
+                'className' => 'MyExtension\\Controller\\Controller2',
+                'alias' => 'Controller2',
+                'actions' => ['newAction2', 'action4', 'action5'],
+                'nonCacheableActions' => ['action4']
+            ]
+        ];
+        $actualResult = $mergedConfiguration['controllerConfiguration'];
+        $this->assertEquals($expectedResult, $actualResult);
+    }
+
     /**
      * @test
      */
@@ -543,7 +593,9 @@ public function newActionsCanBeAddedForCurrentPlugin(): void
         }));
         $mergedConfiguration = $this->abstractConfigurationManager->getConfiguration();
         $expectedResult = [
-            'Controller1' => [
+            'MyExtension\\Controller\\Controller1' => [
+                'className' => 'MyExtension\\Controller\\Controller1',
+                'alias' => 'Controller1',
                 'actions' => ['action2', 'action1', 'action3', 'newAction']
             ]
         ];
@@ -614,10 +666,14 @@ public function cachingOfActionsCanNotBeChanged(): void
         }));
         $mergedConfiguration = $this->abstractConfigurationManager->getConfiguration();
         $expectedResult = [
-            'Controller1' => [
+            'MyExtension\\Controller\\Controller1' => [
+                'className' => 'MyExtension\\Controller\\Controller1',
+                'alias' => 'Controller1',
                 'actions' => ['newAction', 'action1']
             ],
-            'Controller2' => [
+            'MyExtension\\Controller\\Controller2' => [
+                'className' => 'MyExtension\\Controller\\Controller2',
+                'alias' => 'Controller2',
                 'actions' => ['newAction2', 'action4', 'action5'],
                 'nonCacheableActions' => ['action4']
             ]
diff --git a/typo3/sysext/extbase/Tests/Unit/Configuration/FrontendConfigurationManagerTest.php b/typo3/sysext/extbase/Tests/Unit/Configuration/FrontendConfigurationManagerTest.php
index 87ef21f60bb6..88be283b90cc 100644
--- a/typo3/sysext/extbase/Tests/Unit/Configuration/FrontendConfigurationManagerTest.php
+++ b/typo3/sysext/extbase/Tests/Unit/Configuration/FrontendConfigurationManagerTest.php
@@ -305,26 +305,32 @@ public function overrideSwitchableControllerActionsFromFlexFormMergesNonCacheabl
             'pluginName' => 'Pi1',
             'extensionName' => 'SomeExtension',
             'controllerConfiguration' => [
-                'Controller1' => [
+                'MyExtension\\Controller\\Controller1' => [
+                    'alias' => 'Controller1',
                     'actions' => ['action1 , action2']
                 ],
-                'Controller2' => [
+                'MyExtension\\Controller\\Controller2' => [
+                    'alias' => 'Controller2',
                     'actions' => ['action2', 'action1', 'action3'],
                     'nonCacheableActions' => ['action2', 'action3']
                 ]
             ]
         ];
         $flexFormConfiguration = [
-            'switchableControllerActions' => 'Controller1  -> action2;Controller2->action3;  Controller2->action1'
+            'switchableControllerActions' => 'Controller1  -> action2;\\MyExtension\\Controller\\Controller2->action3;  Controller2->action1'
         ];
         $expectedResult = [
             'pluginName' => 'Pi1',
             'extensionName' => 'SomeExtension',
             'controllerConfiguration' => [
-                'Controller1' => [
+                'MyExtension\\Controller\\Controller1' => [
+                    'className' => 'MyExtension\\Controller\\Controller1',
+                    'alias' => 'Controller1',
                     'actions' => ['action2']
                 ],
-                'Controller2' => [
+                'MyExtension\\Controller\\Controller2' => [
+                    'className' => 'MyExtension\\Controller\\Controller2',
+                    'alias' => 'Controller2',
                     'actions' => ['action3', 'action1'],
                     'nonCacheableActions' => [1 => 'action3']
                 ]