I don´ t know which plugin, but last thing I did was to manually upgrade my WP´s plugins.
One instant later, my WP site was down 🙁
Yeah, that´s why you should have a staging site. Or a copy of your site in a development box. Maybe bring a copy to Cloud9 and test it before you deploy any change or update on your site.
How to solve this issue?
#1: While in your cPanel screen, find the phpMyAdmin application. (or SSH into the server).
#2: Find your <table>_options table.
#3: Filter over column “option_name” for an entry having value “active_plugins”. Result will give you something like
#4: Run an UPDATE sentence by changing only “a:1” to “a:0”. This disables all plugins installed on your WP site.
#5: If this was the root cause, at least it was on my case, your WP site should come up when accessing it. For me, when error was live, I was getting a PHP error which I don´t remember.
#6: Go to plugins, update them as needed (even if they are deactivated).
#7: Now, one by one, activate each of them. Every time you check your site to validate it´s not broken again after activating the plugin.
For me, this fixed my problem. I hopes this helps some body else.