Problem saving to local database. Unknown error.

Hello, I keep getting this error message on Mendeley Desktop 'Problem saving changes to your local database. Unknown error.' I followed all the steps here http://support.mendeley.com/customer/portal/questions/1505858-error-mendeley-desktop-there-was-a-problem-saving-changes-to-your-local-database-the-disk-is-full and I still get the error message. I'm running Linux as well.