Thanks for catching that, both points are fair. On pam_unix, you're right that it doesn't hard-fail on a missing shadow entry, it treats missing aging data as nothing to check rather than a denial. I'd assumed the account phase failure came from that fallthrough without confirming pam_unix's own actual return value, that was an inference, not something I traced directly.
On systemd-user, I only checked /etc/pam.d/systemd-user and didn't check /usr/lib/pam.d/systemd-user, so the "doesn't exist" claim is wrong, my mistake. What I can say for certain from the logs on this specific machine, unix_chkpwd reported "could not obtain user info (gdm-greeter)" at the point of failure, so NSS resolution for that dynamic account genuinely wasn't working here, whatever the underlying reason. This machine had been through a Timeshift restore and a fairly involved dpkg and kernel recovery earlier the same session, so I think something in this particular system's nss-systemd or dbus state was more likely left inconsistent by that, rather than this being a universal 26.04 issue on a clean install. The account-line replacement worked around the symptom, but I can't point to a confirmed root cause for why the NSS lookup itself was failing here. Apologies for stating the mechanism more confidently than the evidence supported. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2167510 Title: GDM login screen never appears after upgrading to 26.04, gdm-greeter dynamic user rejected by pam_unix account check To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gdm3/+bug/2167510/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
