This error code keeps showing up and now Active Directory users can no longer edit documents etc., on SharePoint! Please Help!
I would suggest you do the following in that order:
If that doesn't help and you don't find the cause of the issue, you could recreate the User Profile Service Application. There is a really useful guide on that: http://www.harbar.net/articles/sp2010ups.aspx . It's for SharePoint 2010, but there isn't a big difference between 2013. Fixing User Profile Service can sometimes be a real pain.