If it is on every project (and then even new ones), it means that the problem comes from UE4 or from your PC.
I advise you to clean up your PC with [Glary Utilities][1]. Try to reinstall UE4.
If it still happens, try to take a screenshot and post it (it will be easier to help), and try to force the crash (it can seem random but maybe it’s something over time like memory saturation, or undo history).
I mean this for the repair tool. (By the way I found the picture on this [website][2], maybe it can help you.)
