Hello,

This is a bug that occurs in IE6 that causes certain backends (mongrel/Rails in this case) to die unexpectedly:

Current behavior:

1. A user visits a Rails page in Internet Explorer 6 - certain versions of IE6 may not have this bug but we were able to reproduce it on the majority of our Windows machines.

2. That page returns a "Location" header with an anchor, e.g.:

Location: http://www.example.com/page#zap

3. As a result, IE sends a request as follows:

GET http://www.example.com/page#zap HTTP/1.1 Host: www.example.com etc etc

This is a bug in IE - it should have stripped the #zap from the URL but it does not. If the URL is refreshed, IE correctly removes the anchor before sending it to the server.

4. Upon receiving the request, a "403 Bad Gateway" error occurs because the mongrel process bails.

Expected behavior:

Because this bug could affect a large number of backends (cgi/fastcgi/proxy), nginx should remove the anchor part of the URL before passing it on to any other service.

I will also be passing this on to the mongrel guys.