Why “Content-Length: 0” in POST requests?

Question

A customer sometimes sends POST requests with Content-Length: 0 when submitting a form (10 to over 40 fields).

We tested it with different browsers and

Answer 1

If the user is going through an ISA proxy that uses NTLM authentication, then it sounds like this issue, which has a solution provided (a patch to the ISA proxy)

http://support.microsoft.com/kb/942638
POST requests that do not have a POST body may be sent to a Web server that is published in ISA Server 2006