I only have 1 project where I work on.
I was busy in a blue print window as far I can remember correctly. I was almost at the end of this tutorial: BP Twin Stick Shooter: Building the Enemy Character | 08 | v4.8 Tutorial Series | Unreal Engine - YouTube.
Try to install Linux Mint first. It happens on a Linux machine. I was creating a 3rd person game. Similar to the video I sent to you, nothing really special. Then I closed the window ‘construction script’ in blueprint. I didn’t knew how to bring it back. After all it was not listing in the ‘window’ menu.
So, I decided to reset the layout under Window menu to bring the construction script window back within the bluesprint window.
From that moment Unreal Engine Editor tries to restart, but it failed.
My guess is that some threads are not closed correctly or some other memory cause which results into the signal 11 error at startup.