WordPress stuck with “Briefly unavailable for scheduled maintenance…”

Today I went to update some plugins on one WordPress installation but then I accidentally closed the tab while update was in process. When I went back to WP admin or (to blog homepage) I was getting this error: Briefly unavailable for scheduled maintenance. Check back in a minute.

Since I couldn’t access WP Admin my hands were tied and I could do anything. So I logged in at the FTP to see how the plugins folder looks like and is something damaged.

And in pubic_html folder I noticed file .maintenance. I made backup of it and then deleted it and reloaded the blog and – IT WAS WORKING AGAIN!

And WP admin was working again!

WordPress never stops amazing me!