Several players of Fallout 4 have reported the existence of a game-crashing bug on Bethesda’s forums. The bug is activated by accepting a settlement quest that requires players to head to Monsignor Plaza. At that point, if you go there, the game will crash. This bug has been reported in all versions of the game, and on the PC version, doing things like starting a new game doesn’t seem to fix the problem — once you’ve accepted the quest, you can never go to the Monsignor Plaza area again, making game completion impossible.
While many bugs have been reported in the game, none of them have had the potential to ruin the player’s progress until this one. It’s advised that players of Fallout 4 avoid this particular quest until the glitch is patched up. Bethesda themselves has yet to release a statement regarding the problem.