Strange error opening up project?

Hey there,

I got this bizarre error today while attempting to open a project in the 5.3.5 version of Unity.

The ProjectVersion.txt says that the last saved version is 5.3.5 (matching the version of the editor I launched it with), but the error says it’s from a version before 5.0.

Then to cap it all off I get a fatal error directly after that, the meaning of which I can’t seem to figure out.

Help would be much appreciated.

Really need help on this, guys. No one’s got a clue what this error is or why it’s happening?