Getting weird FastCGI errors?

I've just been having a conversation with Jens, who was getting an 'unable to connect to FastCGI error', which I know seems to be the most common way for this setup to fail.

First was looking at the temporary folder - if it works in WEBrick but not in IIS does it mean that IIS does not have permission to write session files to the temporary folder? In this case, IIS had all the permissions it needed. One thing to watch out for is that I find "Everyone" does not always mean everyone - so it may help to add certain users individually.

Next suggestion was the fast-cgi crash log - which seems to appear in the rails application's log folder. There was none - but it's not always that helpful anyway.

Next up was watching Task Manager as the request goes in - does rubyw.exe appear at all? In this case, no. This is useful as it shows whether the request is passing through FastCGI and it is ruby that cannot start or whether it was FastCGI going wrong. In this case ruby could not start. Why?

One thing that I found useful when installing a Rails application on my personal hosted site (Linux/Apache) was to run dispatch.cgi and dispatch.fcgi manually. Open a command prompt, move to your public folder and run ruby dispatch.cgi - you should get an internal server error. Try the same with dispatch.fcgi - here Jens got a useful error - 'could not load MSVCR71.dll'. It turns out that this is part of the MS C runtime and is a free download. A quick internet search and Jens was up and running.

So, if you are getting weirdness in your FastCGI setup then try downloading MSVCR71.DLL and see if that fixes it.

UPDATE: Not quite working yet, but it looks like its Rails weirdness, not FastCGI weirdness.