You shouldn't upgrade between major Ubuntu (-based) releases like that, as it doesn't account for certain configuration changes, you are bound to hose your syst

You shouldn't upgrade between major Ubuntu (-based) releases like that, as it doesn't account for certain configuration changes, you are bound to hose your system if you do it that way. Ubuntu has another script 'do-release-upgrade', but I'm not sure if Mint has it as well. I do know the recommended way to upgrade Mint is to do a full reinstall while preserving $HOME. There are step-by-step instructions how to do an in-place upgrade somewhere on the Mint site, I followed those once (14 to 15 I think) and it worked perfectly, but it's not recommended.