PROBLEM:

Unable to pass beyond login screen (sddm) using correct credentials.

WHAT HAPPENS:

After boot to cli, I systemctl start sddm, it gives me the usual login screen. I click my user, enter password, hit enter and the field freezes. I can still move the cursor, but can no longer interact with any user portraits/fields etc.

- If I leave it for several hours, nothing has changed. I can only get
away from this by systemctl stop sddm.
- If I try entering the wrong password, it tells me such and I can try again.
- If I try logging in to a different user, this works,

...leading me to believe it could be something about the user's config causing it.

ATTEMPTS TO FIX/DIAGNOSE:

I've appended BAK to all .bash*** files under the affected user. This has no affect to the outcome.

Trying to start KDE manually with startkde results in DISPLAY is not set or cannot connect to the X server.

~/.local/share/sddm/xorg-session.log contains /usr/bin/xauth: timeout in locking authority file ~/.Xauthority

No protocol specified

There is no .Xauthority file present.

FIX:

I started focusing on the xauth error, did some research and found recommendations to use strace xauth, this gave me errors such as permission denied, I checked and the user's home directory (top level and several child files/folders) had become owned by root.

So I did chown -Rf <myuser>:<myusergroup> the top level directory and now everything works fine whilst trying to login to the specific user within sddm/kde.