I've been messing with my server today as I upgraded it to Rails 2. One of the things I did too is update totally Rails on my Mac, and then, when code was up to date and everything worked, I uploaded as a brute the files.

I even uploaded public/dispatch.fcgi . That's when things started to go terribly wrong. As I made other small changes, it took some time to find out, but my lighttpd server was stopping whenever I tried to reload it with a message like this :

2008-03-21 18:29:27: (mod_fastcgi.c.999) execve failed for: /www/guide/public/dispatch.fcgi No such file or directory 
2008-03-21 18:29:27: (mod_fastcgi.c.1025) the fastcgi-backend /www/guide/public/dispatch.fcgi failed to start: 
2008-03-21 18:29:27: (mod_fastcgi.c.1029) child exited with status 2 /www/guide/public/dispatch.fcgi
... And so on

Turns out Mac F.. OS X.5 has a special path for Ruby, something like #!/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby which is quite different from the one I hav on my Ubuntu server : #!/usr/local/bin/ruby. That single line caused all the trouble, but none of the error messages pointed to that direction.