The machine was running Debian wheezy and was recently upgraded to Jessie. Everything has worked fine for some time. However, after a reboot today the desktop won't load.
/var/log/messages shows gnome-shell: segfault at 0 error 4 in libupower-glib.so.3.0.0
I have tried reinstalling gnome-session, gdm3, libupower.
(Sorry about the formatting, I'm on a phone.)