/usr/bin/gnome-boxes:6:g_assertion_message:g_assertion_message_expr:boxes_app_setup_default_source_co:g_simple_async_result_complete:boxes_app_add_collection_source_co

The Ubuntu Error Tracker has been receiving reports about a problem regarding gnome-boxes. This problem was most recently seen with package version 3.22.3-1, the problem page at https://errors.ubuntu.com/problem/267ec3095ecc3a2e514a944847993816696fa22d 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 you can request it at http://forms.canonical.com/reports/.