MySQL fails to start after upgrade to 12.04? or Solving MySQL ERROR socket 2002

Check that mysql-server-5.1 package was uninstalled, seems it might persist after upgrade. I had the same error and had to purge MySQL server 5.1 and 5.5 then re-install. First make a backup of your /var/lib/mysql/ directory just to be safe. sudo mkdir /home//mysql/ cd /var/lib/mysql/ sudo cp * /home//mysql/ -R Next purge MySQL (this will remove php5-mysql and phpmyadmin as well as a number of other libraries so be prepared to re-install some items after this. sudo apt-get purge mysql-server-5.1 mysql-common Remove the folder /etc/mysql/ and it's contents sudo rm /etc/mysql/ -R Next check that your old database files are still in /var/lib/mysql/ if they are not then copy them back in to the folder then chown root:root (only run these if the files are no longer there) sudo mkdir /var/lib/mysql/ sudo chown root:root /var/lib/mysql/ -R cd ~/mysql/ sudo cp * /var/lib/mysql/ -R Next install mysql server sudo apt-get install mysql-server Finally re-install any missing packages like phpmyadmin and php5-mysql.