/usr/lib/mate-panel/appmenu-mate:11:g_type_check_instance:g_signal_emit_valist:g_signal_emit:g_menu_model_items_changed:queue_emit_all

[errors.ubuntu.com bug bridge]

The Ubuntu Error Tracker has been receiving reports about a problem regarding vala-panel-appmenu. This problem was most recently seen with package version 0.6.94+repack1-2, the problem page at https://errors.ubuntu.com/problem/72dce8439eceb0358b59c15430856fbc8b8eaf6b 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/.