Typo3 - Folder "/" does not exist - Error


when I am in the backend in the filelist Module or want to link something, I get the error message: “#1314516810: Folder “/” does not exist.” (see screenshot). The folder exists of course, and everything worked until recently, the error suddenly appeared from one day to the next. I checked the fileadmin settings too and everything seems fine (see screenshot). I have already googled the error and searched several forums, but I cannot find a solution to my problem.

Does anyone have an idea what the problem is and how I can fix it? Thank you very much in advance.

Typo3-Version 8.7.32
Webserver: Apache
PHP-Version: 7.4.28
Database: MariaDB 10.3.34
OS: Ubuntu 20.04.4 LTS
Server Management via Plesk Obsidian 18.0.43


typo3 folder error