It was a C++ project that I was working on for a few days.
The last thing I was working on was mouse-over events for objects in the scene in the C++ code (I didn’t have this working properly on my last exit, so i suspect it’s to do with this).
The editor closed down correctly the last time I was working on it, but upon trying to open the project again, the editor just crashes.
I was opening it from the launcher.
Sorry, but I can’t help with the last points. I decided to delete the project and UE4.9 and download 4.10 instead to start fresh. I was posting this to report the bug but I now realise I have deleted everything prematurely which probably doesn’t help you guys at all.
You can close this thread as I have started over with UE4.10. Sorry about that!
I will mark this as answered by request for tracking purposes. If you experience this error again in 4.10, please feel free to post here with updated information and I’ll be happy to take another look.