/usr/bin/dolphin:6:qt_message_fatal:QMessageLogger::fatal:QXcbConnection::QXcbConnection:QXcbIntegration::QXcbIntegration:QXcbIntegrationPlugin::create

The Ubuntu Error Tracker has been receiving reports about a problem regarding dolphin. This problem was most recently seen with package version 4:16.04.3-0ubuntu1, the problem page at https://errors.ubuntu.com/problem/b798b4eed3987eba30d72d22919466b2116a1eb4 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/.