diff --git a/typo3/sysext/backend/Classes/Controller/ContentElement/ElementInformationController.php b/typo3/sysext/backend/Classes/Controller/ContentElement/ElementInformationController.php
index 4cd55c9b8f146799018eb484a47af45a6d32d217..e6c225c41a78ed08bdd2d260e698bd01e9e9fb23 100644
--- a/typo3/sysext/backend/Classes/Controller/ContentElement/ElementInformationController.php
+++ b/typo3/sysext/backend/Classes/Controller/ContentElement/ElementInformationController.php
@@ -259,7 +259,7 @@ class ElementInformationController
                 $view->assignMultiple($this->getPreview());
                 $view->assignMultiple($this->getPropertiesForTable());
                 $view->assignMultiple($this->getReferences($request));
-                $view->assign('returnUrl', GeneralUtility::sanitizeLocalUrl($request->getQueryParams()['returnUrl']));
+                $view->assign('returnUrl', GeneralUtility::sanitizeLocalUrl($request->getQueryParams()['returnUrl'] ?? ''));
                 $view->assign('maxTitleLength', $this->getBackendUser()->uc['titleLen'] ?? 20);
                 $content .= $view->render();
             }
diff --git a/typo3/sysext/core/Tests/Acceptance/Backend/FormEngine/InlineFalCest.php b/typo3/sysext/core/Tests/Acceptance/Backend/FormEngine/InlineFalCest.php
new file mode 100644
index 0000000000000000000000000000000000000000..f13e90c49527a0cfb7772626ee0bb8f92ab68c94
--- /dev/null
+++ b/typo3/sysext/core/Tests/Acceptance/Backend/FormEngine/InlineFalCest.php
@@ -0,0 +1,98 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the TYPO3 CMS project.
+ *
+ * It is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License, either version 2
+ * of the License, or any later version.
+ *
+ * For the full copyright and license information, please read the
+ * LICENSE.txt file that was distributed with this source code.
+ *
+ * The TYPO3 project - inspiring people to share!
+ */
+
+namespace TYPO3\CMS\Core\Tests\Acceptance\Backend\FormEngine;
+
+use TYPO3\CMS\Core\Tests\Acceptance\Support\BackendTester;
+use TYPO3\CMS\Core\Tests\Acceptance\Support\Helper\ModalDialog;
+use TYPO3\CMS\Core\Tests\Acceptance\Support\Helper\PageTree;
+
+/**
+ * Tests for inline fal
+ */
+class InlineFalCest
+{
+    protected static string $filenameSelector = '.tab-content .form-irre-header-cell .form-irre-header-body dd';
+    protected static string $saveButtonLink = '//*/button[@name="_savedok"][1]';
+
+    /**
+     * Open styleguide inline fal page in list module
+     *
+     * @param BackendTester $I
+     * @param PageTree $pageTree
+     * @throws \Exception
+     */
+    public function _before(BackendTester $I, PageTree $pageTree)
+    {
+        $I->useExistingSession('admin');
+
+        $I->click('List');
+        $I->waitForElement('svg .nodes .node');
+        $pageTree->openPath(['styleguide TCA demo', 'inline fal']);
+        $I->switchToContentFrame();
+
+        $I->waitForText('inline fal', 20);
+        $editRecordLinkCssPath = '#recordlist-tx_styleguide_inline_fal a[data-bs-original-title="Edit record"]';
+        $I->click($editRecordLinkCssPath);
+        $I->waitForText('Edit Form', 3, 'h1');
+    }
+
+    /**
+     * @param BackendTester $I
+     * @param ModalDialog $modalDialog
+     */
+    public function seeFalRelationInfo(BackendTester $I, ModalDialog $modalDialog)
+    {
+        $infoButtonSelector = '.tab-content button[data-action="infowindow"]';
+
+        $filename = $I->grabTextFrom(self::$filenameSelector);
+        $I->click($infoButtonSelector);
+        $modalDialog->canSeeDialog();
+        $I->switchToIFrame('.modal-iframe');
+        $modalTitle = $I->grabTextFrom('.card-title');
+        $I->assertContains($filename, $modalTitle);
+    }
+
+    /**
+     * @param BackendTester $I
+     */
+    public function hideFalRelation(BackendTester $I)
+    {
+        $hideButtonSelector = '.tab-content .t3js-toggle-visibility-button';
+
+        $I->click($hideButtonSelector);
+        $I->click(self::$saveButtonLink);
+        $I->seeElement('.tab-content .t3-form-field-container-inline-hidden');
+    }
+
+    /**
+     * @param BackendTester $I
+     * @param ModalDialog $modalDialog
+     */
+    public function deleteFalRelation(BackendTester $I, ModalDialog $modalDialog)
+    {
+        $deleteButtonSelector = '.tab-content .t3js-editform-delete-inline-record';
+        $filename = $I->grabTextFrom(self::$filenameSelector);
+
+        $I->click($deleteButtonSelector);
+        $modalDialog->canSeeDialog();
+        $I->click('button[name="yes"]', ModalDialog::$openedModalButtonContainerSelector);
+        $I->switchToContentFrame();
+        $I->click(self::$saveButtonLink);
+        $I->dontSee($filename, '.tab-content .form-section:first-child');
+    }
+}