My Rails application is only giving me a blank screen, with no HTML at all

Question

I have an app that I haven't worked with in a month or so. I just tried to pull it up, and it is giving me only a blank screen. I am running in dev mode, and monitoring the log. The log shows that everything is OK, in that it is processing the appropriate controller and views.

The nginx log shows no errors. How can I troubleshoot what is happening? This is a Rails 3.0.9 application.

This appears to be a Passenger issue. Unfortunately, Passenger isn't writing any errors that I can see in the logs. I'm getting 200's from nginx also. I have never see something return no HTML at all without errors before.

Update: This is the output from curl -I http://mcp.com (note that I have mcp.com aliased to localhost)

HTTP/1.1 200 OK
Content-Type: text/html; charset=utf-8
Content-Length: 0
Connection: keep-alive
Status: 200
X-Powered-By: Phusion Passenger (mod_rails/mod_rack) 3.0.7
ETag: "17676b3c3d3b322365c8d431f62f944b"
X-UA-Compatible: IE=Edge,chrome=1
X-Runtime: 9.088870
Set-Cookie: _mcp5_session=BAh7CCIQX2NzcmZfdG9rZW4iMVNGRHZ1WVNLZFRIeTh1Sm1lNytyVEU3TkhmQU1pVWZSdXBud2htcFRHSGs9IhRlbnRyeV9zdWJkb21haW4iACIPc2Vzc2lvbl9pZCIlMjA1NGIxNTRmN2M2NTQyNDU1ZTVmZjExYzRjNDhlMTY%3D--c3d21d4bb07a4989243b655aff3d49863d8c81f7; domain=.mcp.com; path=/; HttpOnly
Cache-Control: max-age=0, private, must-revalidate
Server: nginx/1.1.4 + Phusion Passenger 3.0.7 (mod_rails/mod_rack)

Answer 1

Usually that's caused by an exception in production mode, so to see it in dev mode might be an artifact of your server. Investigate if your launcher, like Passenger, is working correctly or not.

If script/console or rails console starts up okay, and you can access it through script/server or rails server then you should be able to narrow it down to the web server level.