Recently I had one of my Wordpress sites lock up with an error message.
I was updating the plugins that are installed on the site. I had 5 that needed updating so I did a bulk update. The first two no problem. Then it got to Jetpack and I waited and waited and waited. No success.
Then I tried changing the window, and it would not let me into any other area of the website. I closed the window hoping everything would shut down, then I could log back in. Nope!
The visible part of the site just gave me an error message referring to Jetpack.
Can't Login and people can't view the site. Not good.
A google search did help and what I found was pretty easy (once I found it). Since Jetpack was the problem All I needed to do was backup the Jetpack folder through ftp on my home computer. Then delete Jetpack off the sever.
Doing this gave me access to the admin area again and I could see and work with the site again. Very helpful. It also pays to have regular backups of the sites!
Here is the link to the article I found on google that helped with this locked situation. There are a couple of alternative solutions as well.