Mahara: Site unavailable

The "root" user is missing from the database so we cannot continue. This user needs to be present for Mahara to function correctly. To add the root user back in please make another install of the Mahara version you are using and see what is contained for user id = 0 in the "usr" and "usr_custom_layout" tables and add that data back in to your instance of Mahara before trying to upgrade again.