I was a bit desperate today, while trying to update my owncloud from version 8.2.1 to 8.2.2. I always got this message in red characters.
Update failed. Unable to move /DOCUMENTROOT/_oc-upgrade/18.104.22.168/core/resources to /DOCUMENTROOT/resources
First I thought the problems were wrong permissions, but the solution is much easier. The owncloud version number in the file
must be 8.2 (see screenshot above)!
In my file it was 8.1. Just change it and start the update again, then it will work :)