/usr/bin/gnome-shell:11:g_type_check_instance_cast:free_fetch_user_request:fetch_user_incrementally:on_find_user_by_name_finished:g_task_return_now

The Ubuntu Error Tracker has been receiving reports about a problem regarding gnome-shell. This problem was most recently seen with package version 44~rc-1ubuntu2, the problem page at https://errors.ubuntu.com/problem/d85747462e756cb405d1e87b9c59b0b995a7d394 contains more details, including versions of packages affected, stacktrace or traceback, and individual crash reports.
If you do not have access to the Ubuntu Error Tracker and are a software developer, you can request it at http://forms.canonical.com/reports/.