I'm guessing this is due to a PHP upgrade, as I upgraded Apache2 and PHP on my ubuntu server and now nginx is no longer functioning properly.
I've restarted the nginx process and fast CGI and it's obviously not working properly and states that FastCGI sends a blank message in stderr. I'm kind of at a loss on how to continue debugging.
Does anyone have any ideas on what step I should take next to debug?
I had a similar problem a few weeks back. turned out to be an issue with permissions. make sure your server root directory, all the files and directories it contains and the entire path to the server root has the correct permissions (don't forget to check the chmod in addition to the ownership).