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

Microsoft's hotfix for KB821814 can set Content-Length to 0:

The hotfix that this article describes implements a code change in Wininet.dll to:

• Detect the RESET condition on a POST request.
• Save the data that is to be posted.
• Retry the POST request with the content length set to 0. This prevents the reset from occurring and permits the authentication process to complete.
• Retry the original POST request.