Backend Error message The path is not a directory. Path:

I updated Joomla from 3 to 4, everything is ok so far and I can use everything. But I have this message: Joomla\CMS\Filesystem\Folder::files: Der Pfad ist kein Verzeichnis. Pfad: Joomla\CMS\Filesystem\Folder::files

How do I get rid of what's wrong? Where can I adjust this?
greetings, Monika