I am making an HTTP connection to an IIS web server and sending a POST request with the data encoded using Transfer-Encoding: chunked. When I do this, IIS simply closes the connection, with no error message or status code. According to the HTTP 1.1 spec,
All HTTP/1.1 applications MUST be able to receive and decode the "chunked" transfer-coding
so I don't understand why it's (a) not handling that encoding and (b) it's not sending back a status code. If I change the request to send the Content-Length rather than Transfer-Encoding, the query succeeds, but that's not always possible.
When I try the same thing against Apache, I get a "411 Length required" status and a message saying "chunked Transfer-Encoding forbidden".
Why do these servers not support this encoding?
Take a look at your client.
Both IIS & Apache support POST requests using chunked transfer-encoding. You can verify this using the curl utility:
curl <upload-url> --form "upfile=@<local_file>" --header "Transfer-Encoding: chunked"
Verify the transfer is chunked using Wireshark