Cannot create new document in Nextcloud (Hetzner Storage-Share)

[mamo2021]

When I try to create a new file in Nextcloud 28.0.6 (Hetzner Storage Share) following Messeage appears:

Fehler: Erstellen einer neuen Datei fehlgeschlagen

Translated:
Error: Failed to create a new file

I can't read the logs. So that's the only information I can give you. In previous versions of nextcloud the app worked fine.
Opening an existing file is no problem.

I have write-permissions to the folder.

In the app-preferences no changes were made.

Any ideas what I could do?