path issues with group folders?

Server

Operating System: Debian 10 (buster)
Web Server: Apache/2.4.38
Database: mariadb Ver 15.1
PHP: 7.3.19
Nextcloud: 19.0.4

Client

Operating System: Windows 10 Pro (1903)
Nextcloud Client: 3.0.2

Error

I am getting the following error message (100+ times) on the server side:

[core] Error: unable to rename, source directory is not writable : /nextcloud_data//some_folder/some_folder/some_folder
MOVE /remote.php/dav/files/user/some_folder/some_folder/some_folder/some_folder
from 123.123.123.123 by user at yyyy-mm-ddThh:mm:ss+00:00

the corresponding error on the client:

**# timestamp:** 
**duration:**
**file:** some_folder/some_folder/some_folder/some_folder -> !__some_folder/some_folder
**instruction:** INST_RENAME
**dir:** Up
**modtime:** >>removed<<
**etag:** >>removed<<
**size:** 0
**fileId:** >>removed<<
**status:** 2
**errorString:** Server hat "403 Forbidden" auf "MOVE https://>>nextcloud<</remote.php/dav/files/user/some_folder/some_folder/some_folder/some_folder" geantwortet
**http result code:** 403
**other size:** 0
**other modtime:** 0
**other etag:**
**other fileId:**
**other instruction:**

i replaced sensitive information with dummy values or >>removed<< it completely

I am assuming there is some issue with the path that is not writeable because it does not exist.
All the folder permissions for /nextcloud_data/ and it's sub-folders should be correct and are working for other users, and are working for all of them when the web interface ist used.

what the path looks like:
/nextcloud_data//some_folder/some_folder/some_folder

what i guessthe path should look like:
/nextcloud_data/__groupfolders/groupfolder_id/some_folder/some_folder/some_folder

Thanks for your support!

Start with the server-side error for the WebDAV MOVE request and compare its resolved path with the expected /__groupfolders/groupfolder_id path; the client’s 403 response provides the matching symptom. Done means the group-folder path is resolved correctly for this rename and the request no longer fails with a non-writable source directory.