So, after several tries I find tricky solution. I delete the VehicleAdvGameMode, then when the editor already loaded, I reset file and in 2 of 10 tries I can open it. So, I just create new GameMode and copy everything from VehicleAdvGameMode when editor didn’t crash (I don’t know why some times it open it and didn’t crash). And one more thing, I found a strange field “Thumbnail” in broken VehicleAdvGameMode (in my new one with the same parent it not appear), so I think this is was the one of the things what cause crash.