Passenger broken by recent upgrades

I have been running a ruby on rails app for the past two years, and recently my service was moved from the paulreedsmith server to the nott server. After this move, my rails app has stopped working.

There is nothing logged in the rails application logs (logs/production.log), and there are no logs in the http error logs. The access log shows an attempt to access (e.g. GET request) but nothing more.

I have of course touched tmp/restart.txt many many times. The server always just returns a 500 error with no useful information:

I really have no idea what to do. I have contacted support to find out if they have more logs to provide, but they claim there is no additional information and suggest my configuration is bad–the same configuration that has been in place for years.

I ran mongrel and the application works fine when running on port 3000, using the built-in rails webserver. I don’t think I can run it on port 80 because I don’t think I have high enough privileges to bind to any port that low.

Has anyone encountered this error or have any suggestions on troubleshooting? I feel kind of ridiculous troubleshooting “in the dark” without logged errors…