How to get out of the maintenance mode of Wordpress after failed plugin upgrade

This morning, I was trying to upgrade some plugins on my Wordpress blog. The process failed and the whole site showing this message:

"Briefly unavailable for scheduled maintenance. Check back in a minute."


I tried to refresh the page, nothing happen. The blog's frozen there.

So, to get out of the maintenance mode of Wordpress, just delete the .maintenance file in the root folder of the wordpress blog. For example:

$ sudo rm /var/www/wordpress/.maintenance