For the past week or two, I've noticed my login process to be slightly different than normal. This made me wonder if there is a security issue I should worry about. So I started searching here, but could not find a clear answer.
I see many questions about being caught in a "login loop" but that is not what is happening to me (at least I do not think so).
When I startup my laptop running 18.04 (encrypted boot drive, up to date OS) I have to enter my decryption password. This is as it has always been. Then, I am greeted with the normal login screen. I enter my password and it looks like it was accepted (no bad password message, the screen is all purple momentarily but I can still see the mouse cursor, but I cannot move it) and before the desktop background (or any desktop icons) shows, I am returned to the normal login screen. There is still no message to indicate that my password was wrong. I enter the password, again, and it starts as usual.
What is so strange to me is that this is always a double login. That is, it never prompts me only once and it never prompts me more than twice.
I looked for the ~/.xsession-errors file but I do not seem to have it.
I've used this laptop for a year with 16.04 and I installed 18.04 just after it was released and there have been no hardware changes.
Any ideas?
I had this same issue when upgrading from 16.04 to 18.04. For me it was related to Ubuntu switching from Xorg to Wayland.
When booting Ubuntu it was starting a Wayland session, but my user session was still configured to use Xorg from my 16.04 install, causing the double login scenario when it switches to Xorg. I was able to fix the issue by setting my user session to use
Ubuntu on Waylandi had the issue after upgrading from 16 to 18. And 'accidentally' fixed it after reinstalling the graphics card drivers. Anyone still having the issue might wanna try this as well.
I've been getting this issue since upgrading from 18.04 LTS to 18.10. Logging into Ubuntu on Wayland (as John suggests above) did not work because the session would crash, logging me out after about five seconds of uptime.
I noticed that another option was listed under Ubuntu on Wayland, called Ukui, and when I logged into that everything was completely broken.
I uninstalled Ukui, and it fixed the problem! The double login screen is gone.
I don't know why this broken desktop environment was ever installed in the first place, but here's how I removed it:
I also found several other Ukui programs installed using this command
... all of which I removed: