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.