HELP! cubase made project corrupt after import from project

just did a “import tracks from project”

after doing that, cubase said my current project is corrupt (not the one i imported from, but the active one, the one ive imported to.

now i cant save my project, cant back up , nothing, cubase tells me the project is corrupt.
what do i do?!?! HELP!!!

I only can say, make sure to make extra versions of your project.

However when closing cubase and reopening the project, what does happen then?