Disregard!  Apparently there was an update somewhere, or I changed the right setting in DSM and I was able to get it to work across all platforms.  I created a new folder and basically started from scratch and went into every permission and security setting I could find to ensure they were set properly. 

Sync is working for me now.  DSM 7, current WebDAV, and clients on Windows, iOS, and MacOS. 

Good morning.  I had this same error with both my PC and Android on DSM 6.2 and DSM 7.0, some time around June/July 2021 syncing stopped.  After the upgrade to DSM 7.0 I thought that would fix the issue.  I looked to convert the permissions to ACL as noted here but tried something else first.  What solved my issues was leaving the permissions as they were but I went into the  file station, to the webdav folder, I right clicked on the folder where I store Enpass, went to properties, and checked, "apply to this folder, sub-folders and files" under owner this re-pushed the folder permissions down again and after I did that everything started working again. 

It appears an update may have broke the permissions on the webdav folders, that's why converting to ACL or re-pushing permissions seem to work.

Just passing along what worked for me.

 

Any Updates here? The current solution is quite disapointing if you have more user on the NAS and they're using their Home folders.

 

Also the same issue does not come up with other WebDav services / Apps

Edited October 12, 20214 yr by chase

I've created a ticket and they sent me the following link with the newest release 2.4.2. For me it's working again without any further changes (Windows ACLs,...). Finally!

https://supfiles.synology.com/fsdownload/cJ5c835mF/KI43117

I was just about to report my workaround with a docker container, then I saw s-bahn's response

 

Thank you for sharing the link!