Black screen after logging in, after upgrading to 20.04
Solution 1:
I thought it was gonna take hours but I found .config/dconf/user to be the culprit. Removing that file restored my ability to login without ending up in a black screen.
Solution 2:
I had this problem, and found out that it was because of my radeon driver. According to Can't Log In or Black Screen After Logging In with Ubuntu I blacked list it and everything worked just fine.