by Ken Task.
Did you click that link that has more information about this error?
It points to:
https://docs.moodle.org/27/en/error/moodle/dmlwriteexception
and on that page it says:
"If you're using a MySQLdatabase for your Moodle installation, this error can be caused by the server's max_allowed_packet size being configured incorrectly."
Tracker Item says 'fixed':
https://tracker.moodle.org/browse/MDL-46651
Did see a suggestion to run cron.
And you might want to run the health tool
http://yoursite/admin/tool/health/ to see what it says about quiz banks.
'spirit of sharing', Ken