I haven’t really used the File manager, but just now I had a complaint from a user trying to access it. The error was “Unknown Error”, and nothing from this thread seemed to work. Even stranger, some users were able to use the File Manager, and some weren’t.
In /var/log/auth.log there was an entry saying "fatal: bad ownership or modes for chroot directory “/home/user”, so I started looking around. Eventually I discovered that the users who couldn’t log in had their .ssh directory permissions set to 700, whereas those who could login had the .ssh directory set to 755. Changing the permissions on the .ssh directory fixed it for me, and those who were getting the error (including the admin user) were now able to use the file manager.
So this poses a bit of a problem. .ssh directories should officially be set to 700, shouldn’t they? Private keys need to be 600, so I guess no massive problem if the .ssh directory is a bit more permissive, but it makes me uneasy.