The X-File-MD5 header must not be null

I have alot of this error message in my nextcloud.log:

{"reqId":"WzoWHlRGQJLam5Ui4M7Y","level":3,"time":"2023-08-19T19:51:49+00:00","remoteAddr":"","user":"yarn","app":"no app in context","method":"POST","url":"/remote.php/dav/bulk","message":"The X-File-MD5 header must not be null.","userAgent":"Mozilla/5.0 (Windows) mirall/3.9.2stable-Win64 (build 20230808) (Nextcloud, windows-10.0.19045 ClientArchitecture: x86_64 OsArchitecture: x86_64)","version":"","data":[]}

Newly installed Nextcloud (27.0.2) on Debian 12. Cant find any similar error message when I google around.

Think I found the issue. The problem happens when editing a docx (for example). It creates a temporary file starting with ~$ that should not be synced.

When checking the ignored files in the Windows client it was empty. It is strange, as the client was newly reinstalled. Clicking on the “Restore Default”-button in the Windows clients settings solved the problem.