How to debug failed changes to posts?

I was finally able to get this to work by using php5-fpm instead of php5-cgi. First I removed the php5-cgi package via

sudo apt-get autoremove --purge php5-cgi

Then I installed php5-fpm via:

sudo apt-get install php5-fpm

After tweaking my server definition in Nginx a bit, the problem went away.

Update
I suspect this had more to do with a faulty Virtual Host file for my website then php5-cgi.