I had an Ubuntu 19.04 with automatic login enabled (desktop PC). After the upgrade to 19.10 I could no longer log in successfully. After booting an unlock screen was displayed where I could select my username, then enter my password and then click "Unlock". However after entering my password and clicking "Unlock" or pressing Enter nothing would happen and I would stay in the unlock screen. Even the shutdown and restart menu actions would work. A count down would be displayed but nothing would happen after it reached 0.
I had to boot with an old kernel (5.0.0-31-generic) to which I could still log in automatically, disable automatic login and then reboot so that I could successfully log in again with the new kernel. Enabling automatic login again causes the issue to appear again.