I believe that I've found the problem! Using the technique that Ludo’ described in , I was able to grab an strace of gdm (attached) while it was failing to start properly. I was suspicious of the following line: """ 418 22:46:10 sendto(8, "<13>Jan 26 22:46:10 gdm: GdmManager: couldn't look up username gnome-initial-setup\n", 83, MSG_NOSIGNAL, NULL, 0) = 83 <5.487224> """ so I removed gnome-initial-setup from the propagated-inputs with the following patch, and, indeed, that resolved the problem with gdm on my system. While I'm still not exactly sure why this was causing gdm problems, and why `herd restart xorg-server` caused gdm to start working correctly, I think that removing gnome-initial-setup from the gnome meta-package is the right thing to do. Instead, perhaps it could be provided via its own service, auto-selected by the installer. If I recall correctly from other distros (e.g. Fedora), the gnome-initial-setup wizard is run from its own user on first boot, and after it finishes, the user is logged in as themselves. That said, gnome-initial-setup did seem to run fine for me the first time I logged into gnome after it was installed, and hasn't stared again. Thoughts? Jack P.S. Thanks Raghav for your work on making gnome in guix a better experience!