Private AccessPrivate Access
This function’s access is marked private. This means it is not intended for use by plugin or theme developers, only in other core functions. It is listed here for completeness.
Die with a maintenance message when conditions are met.
Checks for a file in the WordPress root directory named ".maintenance". This file will contain the variable $upgrading, set to the time the file was created. If the file was created less than 10 minutes ago, WordPress enters maintenance mode and displays a message.
The default message can be replaced by using a drop-in (maintenance.php in the wp-content directory).