So what causes a WordPress blog to start saying “Briefly Unavailable for Scheduled Maintenance…Check back in a minute” and how do you fix it?
The cause is this: When you auto update either WordPress or plugins, WordPress creates a temporary file in the WordPress root so users can’t access the site for a few minutes while the update is performed. Pretty good idea, but if the update fails or for some reason the file is never removed, then both the site and the WordPress backend are not accessible to anyone.
The fix is pretty simple: remove the file and everything will be better again (although if you were doing a WordPress upgrade and it failed, your site may be in an unstable state or your database might still require conversion to the latest version).
The file that needs removing is called
.maintenance (note the preceeding dot – it is important) and should reside in the WordPress root directory (where index.php and wp-content reside). Connect via ssh or ftp and remove this file and the site should be back online.
One other note – the preceeding dot on the filename makes it not show in a file listing (at least on Linux). Use
ls -la to show *ALL* files including those that start with a period.