Please note the lines in your log: Jul 3 20:25:07 c6 /etc/mysql/debian-start[20758]: Version check failed. Got the following error when calling the 'mysql' command line client Jul 3 20:25:07 c6 /etc/mysql/debian-start[20758]: ERROR 1698 (28000): Access denied for user 'debian-sys-maint'@'localhost' Jul 3 20:25:07 c6 /etc/mysql/debian-start[20758]: FATAL ERROR: Upgrade failed
It means the credentials in your /etc/mysql/debian.cnf file are not in sync with your actual database tables. This indicates a installation spesific issue, not a general bug, so I'll drop the severity.
