/usr/lib/gvfs/gvfsd-dav:11:certificate_to_string:gvfs_accept_certificate:do_mount:g_vfs_job_run:job_handler_callback

The Ubuntu Error Tracker has been receiving reports about a problem regarding gvfs. This problem was most recently seen with package version 1:1.28.1-2salbabix27xenial, the problem page at https://errors.ubuntu.com/problem/5daf1096f33bbdd424dd32be22c8804182950d7e 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/.