The other day I was looking in to why Django‘s verify_exists validator wasn’t working on a URLField. It turns out that the 404 handler that we were using to generate thumbnails with lighttpd on the media server was serving up 404 error pages with HTTP/1.1 200 OK as the status code. Django’s validator was seeing the 200 OK and (rightfully) not raising a validation error, even though there was nothing at that location.
It took more than the usual amount of digging to find the solution to this, so I’m making sure to write about it so that I can google for it again when it happens to me next year. The server.error-hadler-404 documentation metnions that to send a 404 response you will need to use server.errorfile-prefix. That doesn’t help me a lot since I needed to retain the dynamic 404 handler.
Amusingly enough, the solution is quite clear once you dig in to the source code. I dug through connections.c and found that if I sent back a Status: line, that would be forwarded on by lighttpd to the client (exactly what I wanted!)
Here’s the solution (in Python) but it should translate to any language that you’re using as a 404 handler:
print "Status: 404"
print "Content-type: text/html"
print
print # (X)HTML error response goes here
I hope this helps, as I’m sure it will help me again some time in the future.