TYPO3 Core

The deletion of forms that are placed in a path configured under TYPO3.CMS.Form.persistenceManager.allowedExtensionPaths is not possible, although the creation in these locations works without an error message.
The delete function of FormManagerController is using the ResourceFactory wich checks, if the YAML file of the form is placed in a public location. If this isn't the case (which isn't checked on creation), the PathUtility throws a InvalidFileException which the ResourceFactory interprets as ResourceDoesNotExistException with the message

Tried to access a private resource file "EXT:my_ext/Resources/Private/Forms/test1.form.yaml" from fallback compatibility storage. This storage only handles public files.

Since we can configure a private path for YAML storage and the fact that YAML files aren't public resources in the first place, I suggest removing the check for public locations when saving and deleting forms in the backend.

Example configuration in BaseSetup.yaml

TYPO3:
  CMS:
    Form:
      persistenceManager:
        allowedExtensionPaths:
          10: EXT:my_ext/Resources/Private/Forms/
        allowSaveToExtensionPaths: true
        allowDeleteFromExtensionPaths: true