This message normally means there’s an error in your code that causes Unreal to crash. Probably in one of the constructors you wrote since they are executed when you start the editor.
I recommend taking a look at the log in _Game/Saved/Logs/_Game.log
Hello,
We’ve recently made a switch to a new bug reporting method using a more structured form. Please visit the link below for more details and report the issue using the new Bug Submission Form. Feel free to continue to use this thread for community discussion around the issue.
https://epicsupport.force.com/unrealengine/s/
Thanks