I recently updated my Owncloud to find that I couldn't access to contacts and calendars from WebDav any more. And after tried a few things, it worked again.
At first when I tried to open the link from the browser, I got this error:
User did not have the required privileges ({DAV:}read) for path "principals/username”
I searched online and found the issue open against owncloud on GitHub. https://github.com/owncloud/core/issues/14048
The workaround mentioned in the issue was already in my Owncloud. But I still had the same issue. I couldn't go further since there's no more workaround and the issue was closed. I thought there must be some errors in upgrading Owncloud, because it's in maintenance mode for quite a long time. But anyway, I got a message about a newer version when I logged in as Admin. I decided to upgrade it manually. It wouldn't be worse.
After I'd done that, the app files_encryption for server side encryption didn't work. From the log, it's about using an undefined function. I removed it from the apps folder since I didn't really need it.
After that, when I logged in to admin, there's a message in my admin page telling me to run command "occ encryption:migrate". I did so. Surprisingly, I could sync to both contacts and calendars.
