No progress at all on this #Ubuntu #GDM login failure issue; I can now only use the machine with a PTS console login, then run gnome-session --wayland, and that gives me only basic function, no access to things like User Accounts.
journalctl only gives these two clues, neither of which yields any meaningful Search results (in 2026)
gdm-autologin][]: gkr-pam: no password is available for user
gdm-autologin][]: pam_unix(gdm-autologin:session): session opened for user guest(uid=1005) by guest(uid=0)
gdm-autologin][]: gkr-pam: couldn't unlock the login keyring.
gdm3[841002]: Gdm: GdmDisplay: Session never registered, failing
but console login proves the user has a perfectly good password! GDM3 fails on the auto-login acct, presents the list of users, clicking one lets you enter pw, then bounces back to the acct list screen and any subsequent attempts are shown a non-functional box to enter their pw and a 'back' button that does nothing. 😩

