Upgraded to Ubuntu Natty, and nginx troubles

Just upgraded my home server (where most of my sites are, though this blog is not among them) from Ubuntu Maverick (10.10) to Natty (11.04). The upgrade itself went without any trouble ((note that this server started out with Jaunty, which means that it has been successfully upgraded five times now. Try doing that in Windows… :))), but, after the new OS version came up, most of my sites were down; they just showed blank pages. And, oddly, there was nothing in any logs. I’m using nginx and php-fpm.

After pulling my hair for a while, I noticed that:

  • the problems were restricted to PHP pages, and…
  • … those didn’t work on any of my sites except for the default one (www.dehumanizer.com).

A little googling, and this post came up, the author of which had the same problem, and was able to spot the solution. In the /etc/nginx/fastcgi_params file, the upgrade had added (silently, since I had never modified that file) the following line:

fastcgi_param       SCRIPT_FILENAME         $document_root$fastcgi_script_name;

Commenting it out solved everything. My guess is that, since the file in question is included only in my default web site configuration, the $document_root variable never changes, so all my sites (except the default) were pointing the wrong way. Anyway, that line is apparently unnecessary, though I’ll see if including the /etc/nginx/fastcgi_params file in every virtual host (maybe you are supposed to do that), and uncommenting back that line, also works.