TYPO3 Core

I create a content element. Then I create a form and add this content element. I then preview the form in the form editor (clicking the eye on page icon) and then click on the content element to edit it, save it and then close it. After closing I get an error message instead of showing my edited form:

(1/1) #1298012500 TYPO3\CMS\Extbase\Mvc\Controller\Exception\RequiredArgumentMissingException
Required argument "formDefinition" is not set for TYPO3\CMS\Form\Controller\FormEditorController->renderFormPage.

The content element can be saved (and is saved), but the error message pops up and I have to go back to my form. via form module on the left. This happens on TYPO3 12.4.9 as well as on 9.x (PHP 7.2.34) where I checked for the error also.