I second this post. I too am having the problem and am behind by over a week. I really hope I can find a fix as I have tried numerous things and do not feel I can wait for an answerhub submission.
I just thought I would throw this out there in case anybody is having the same issue as me. I fixed my problem finally by removing a space in the uproject file for the game. Having a space caused the error to happen. I am now able to open it in the root folder without the error. In the binaries I still receive the error.