lightdm_greeter_authenticate: assertion `priv->connected` failed

[JakeGinesin]

After my last pacman -Syu, this greeter would fail to log me in. Typing in my password and pressing enter would yield nothing except an error dumped into /var/log/lightdm/seat0-greeter.log telling me: lightdm_greeter_authenticate: assertion 'priv->connected' failed.

Switching my greeter to lightdm-gtk-greeter fixed the issue. For reference, here are the packages that were upgraded from the aforementioned pacman -Syu (ripped from /var/log/pacman.log:

[2022-09-13T12:44:28-0400] [ALPM] upgraded libglvnd (1.4.0-3 -> 1.5.0-1)
[2022-09-13T12:44:28-0400] [ALPM] upgraded attica (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:28-0400] [ALPM] upgraded ki18n (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:28-0400] [ALPM] upgraded karchive (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:28-0400] [ALPM] upgraded kconfig (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:28-0400] [ALPM] upgraded kcoreaddons (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:28-0400] [ALPM] upgraded kfilemetadata (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:28-0400] [ALPM] upgraded kidletime (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:28-0400] [ALPM] upgraded solid (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:28-0400] [ALPM] upgraded kwidgetsaddons (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:28-0400] [ALPM] upgraded kjobwidgets (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:28-0400] [ALPM] upgraded kdbusaddons (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:28-0400] [ALPM] upgraded kwindowsystem (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:28-0400] [ALPM] upgraded kcrash (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:28-0400] [ALPM] upgraded kglobalaccel (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:28-0400] [ALPM] upgraded kauth (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:28-0400] [ALPM] upgraded kcodecs (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:28-0400] [ALPM] upgraded kguiaddons (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:28-0400] [ALPM] upgraded kconfigwidgets (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:28-0400] [ALPM] upgraded kiconthemes (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:28-0400] [ALPM] upgraded kitemviews (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:28-0400] [ALPM] upgraded kxmlgui (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:28-0400] [ALPM] upgraded kbookmarks (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:28-0400] [ALPM] upgraded knotifications (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:28-0400] [ALPM] upgraded kservice (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:28-0400] [ALPM] upgraded kwallet (5.97.0-4 -> 5.98.0-1)
[2022-09-13T12:44:28-0400] [ALPM] upgraded kcompletion (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:28-0400] [ALPM] upgraded sonnet (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:28-0400] [ALPM] upgraded ktextwidgets (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:28-0400] [ALPM] upgraded kded (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:29-0400] [ALPM] upgraded kio (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:29-0400] [ALPM] upgraded baloo (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:31-0400] [ALPM] upgraded breeze-icons (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:31-0400] [ALPM] upgraded librepo (1.14.4-1 -> 1.14.5-1)
[2022-09-13T12:44:31-0400] [ALPM] upgraded libdnf (0.68.0-1 -> 0.69.0-1)
[2022-09-13T12:44:31-0400] [ALPM] upgraded dnf (4.13.0-1 -> 4.14.0-1)
[2022-09-13T12:44:32-0400] [ALPM] upgraded emacs (28.1-7 -> 28.2-1)
[2022-09-13T12:44:32-0400] [ALPM] upgraded kpackage (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:32-0400] [ALPM] upgraded syndication (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:32-0400] [ALPM] upgraded knewstuff (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:32-0400] [ALPM] upgraded frameworkintegration (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:32-0400] [ALPM] upgraded imagemagick (7.1.0.47-2 -> 7.1.0.48-1)
[2022-09-13T12:44:32-0400] [ALPM] upgraded kactivities (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:32-0400] [ALPM] upgraded kactivities-stats (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:32-0400] [ALPM] upgraded kdeclarative (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:32-0400] [ALPM] upgraded kcmutils (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:32-0400] [ALPM] upgraded kunitconversion (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:32-0400] [ALPM] upgraded kitemmodels (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:32-0400] [ALPM] upgraded kemoticons (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:32-0400] [ALPM] upgraded kparts (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:33-0400] [ALPM] upgraded kdelibs4support (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:33-0400] [ALPM] upgraded kpty (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:33-0400] [ALPM] upgraded kdesu (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:33-0400] [ALPM] upgraded kdnssd (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:33-0400] [ALPM] upgraded kdsoap (2.0.0-1 -> 2.1.0-1)
[2022-09-13T12:44:33-0400] [ALPM] upgraded kholidays (1:5.97.0-1 -> 1:5.98.0-1)
[2022-09-13T12:44:33-0400] [ALPM] upgraded kirigami2 (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:33-0400] [ALPM] upgraded knotifyconfig (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:33-0400] [ALPM] upgraded kpeople (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:33-0400] [ALPM] upgraded kquickcharts (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:33-0400] [ALPM] upgraded kwayland (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:33-0400] [ALPM] upgraded plasma-framework (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:33-0400] [ALPM] upgraded threadweaver (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:33-0400] [ALPM] upgraded krunner (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:33-0400] [ALPM] upgraded syntax-highlighting (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:33-0400] [ALPM] upgraded ktexteditor (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:33-0400] [ALPM] upgraded libluv (1.44.2_0-1 -> 1.44.2_1-1)
[2022-09-13T12:44:33-0400] [ALPM] upgraded libxp (1.0.3-5 -> 1.0.4-1)
[2022-09-13T12:44:33-0400] [ALPM] upgraded serd (0.30.14-1 -> 0.30.16-1)
[2022-09-13T12:44:33-0400] [ALPM] upgraded sord (0.16.12-3 -> 0.16.14-1)
[2022-09-13T12:44:33-0400] [ALPM] upgraded lilv (0.24.18-1 -> 0.24.20-1)
[2022-09-13T12:44:33-0400] [ALPM] upgraded lsd (0.23.0-1 -> 0.23.1-1)
[2022-09-13T12:44:33-0400] [ALPM] upgraded prison (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:33-0400] [ALPM] upgraded qqc2-desktop-style (5.97.0-1 -> 5.98.0-1)
[2022-09-13T12:44:33-0400] [ALPM] upgraded ruby-bundler (2.3.19-1 -> 2.3.22-1)

[JezerM]

Hmm, that's weird. None of the updated packages should interfere with the login process neither to some backend web-greeter could use. Can you provide the full seat0-greeter log at /var/log/lightdm/seat0-greeter.log?

[Dadams2]

I got a similar error after my recent upgrade which appears to be related to the following when running lightdm --test-mode --debug:

[+0.42s] WARNING: Could not create user data directory /var/lib/lightdm-data/dadams: Error creating directory /var/lib/lightdm-data/dadams: Permission denied

despite having the correct directory and permission layouts. Switching back to lightdm-gtk-greeter also worked for me.