How to fix “Briefly unavailable for scheduled maintenance. Check back in a minute.”

The core automatic upgrade feature in worddpress was added with version 2.7. During the automatic upgrade WordPress places a file named .maintenance in the blog root folder. In that time the vistors will see the message Briefly unavailable for scheduled maintenance. Check back in a minute. If your automatic upgrade process failed and your site still shows the “vistors will see the message Briefly unavailable for scheduled maintenance. Check back in a minute.” message.just delete the .maintenance file.

Note .maintenance is a hidden file.