Perhaps a bit off topic for this site, but maybe it will help someone who was stuck like I was.
My laptop is an Asus Q301L (Sonic Master). Occasionally, when disconnecting the wireless keyboard, my "fn" key is stuck on, so the zero key becomes a forward slash, and other keys are changed, as well.
When a High Availability (HA) environment failed over, on the node that became Secondary, the backup jobs did not gracefully handle the change. The Maintenance Plans are supposed to intelligently determine whether each database is Primary or Secondary in an HA environment, and skip the backup if it is not Primary. This check actually fails (practically speaking) if you have "Verify backup integrity" checked.