If you’re having the dreaded Maintenance error when you do the auto update on your WordPress site, see below to fix your problem:

As part of the automatic upgrade WordPress places a file named .maintenance in the blog base folder (folder that contains the wp-admin folder). If that file exists, then vistors will see the message Briefly unavailable for scheduled maintenance. Check back in a minute.

To stop that message from being displayed to vistors, just delete the .maintenance file. The automatic upgrade should be executed again, just in case it failed.