Client crashes when trying to log in to the game.
Microsoft reports a problem on your part. SR No. 1429474794.
Our development team is aware of a crash issue with both Fallout 4 and Skyrim: Special Edition that occurred following the December updates. They are working to get the matter resolved and hope to have this fixed in a future update. The current workaround is playing while offline. More information about this issue can be found here.