With the new Debian Jessie, I found that my PHP pages would all be displayed as blank pages, even though all regular HTML pages would display correctly.

This comes from the fact that the SCRIPT_FILENAME parameter has been removed from the /etc/nginx/fastcgi_params file. A new file, named /etc/nginx/fastcgi.conf, does reintroduce this parameter, but with the official value “$document_root$fastcgi_script_name”, instead of the former value “$request_filename”.

I really do not understand why the new value is the official one upstream, since it does not play well with aliases. So, first, I referenced fastcgi.conf instead of fastcgi_params, since the former seems to be the preferred file now ; and second, I changed my Nginx configuration to define SCRIPT_FILENAME this way:

fastcgi_param SCRIPT_FILENAME $request_filename;