I am no longer able to control my server from the one user I have access to. When performing sudo commands, I am presented with the following error:
USERNAMEHERE is not in the sudoers file. This incident will be reported.
Presumably this cannot be fixed without access to the root username? I can restore from a VM image to prior to the upgrade, but if I were to perform the upgrade again, what should I do differently to avoid this? I didn't see any mention of the sudoers file being overwritten in the process.