Seriously do you think that for software that manages data the proper way is for someone who starts the upgrade process to say "this is not supported, and now we fucked up your database and you cannot recover from that"? They knew that I was upgrading N+2, this is not a surprise - and I did not realize that upgrading N+2 is not supported.
The proper way would be to abort the upgrade upon discovering that I am going for an unsupported way.
The proper way would be to abort the upgrade upon discovering that I am going for an unsupported way.
This is not serious software.