Updated from 5.3.3 to 5.3.4 and can't open project

Just as the title says. I get an error that says the saved project does not match the launched editor…this may require a re-import.

I am unsure how to do a reimport since I can’t open the file at all? Can anybody help?

In case anyone else has the same issue:

http://forum.unity3d.com/threads/your-project-was-last-opened-with-a-different-setup-of-unity-after-delete-library.392356/