This error is absolutely crippling. It is preventing me from opening any of my scenes whatsoever. I originally thought it was due to Unity somehow reverting from 5.2 to 5.1, however I forced an update by DL’ing unity again, but I still am getting the error.
unfortunately you cant downgrade unity without loading a backup of your files , thats why unity says to backup your files before updating , hard way to learn that lesson , just download 5.2 and use that or wait for unity to fix 5.2 then update again , all your files should be fixed again.
I’m having this same issue, except I haven’t changed my Unity version. It was the same version as the last time I opened the project…