405 means "Method Not Allowed". You get such a response for example when you send a http request with "POST" method but "POST" is not allowed. I used "POST" just as an example, it could be any of the other methods, even a custom one. The data you pasted to your message is a mime encoded stuff.
If you use pure HTTP and not HTTPS then install WireShark on your machine and capture the full http conversation and post it up here to get more accurate answers. (Use the output of the "Follow TCP Stream" feature of wireshark: you can reach "Follow TCP Stream" when you right click on a TCP capture entry in the list.)