Maintenance Mode Configuration

You must put your ownCloud server into maintenance mode before performing upgrades, and for performing troubleshooting and maintenance. Please see Using the occ Command to learn how to put your server into the various maintenance modes (maintenance:mode, maintenance:singleuser, and maintenance:repair) with the occ command.

maintenance:mode locks the sessions of logged-in users and prevents new logins. This is the mode to use for upgrades. You must run occ as the HTTP user, like this example on Ubuntu Linux:

sudo -u www-data php occ maintenance:mode --on

You may also put your server into this mode by editing config/config.php.
Change "maintenance" ⇒ false to "maintenance" ⇒ true:

'maintenance' => true,

Then change it back to false when you are finished.