HttpClient setting boundary with content-type

Question

I am using javascript to communicate with a third party service. As part of their authentication process they need the \"multipart/form\" body of the post message including

Answer 1

We solved this by manually clearing and re-adding the content type without validation it seems that the MediaTypeHeaderValue() class doesn't like the boundary tags.

instead of using :

content.Headers.ContentType = new MediaTypeHeaderValue("multipart/form-data; boundary=----FLICKR_MIME_20140415120129--");

we did the following:

content.Headers.Remove("Content-Type");
content.Headers.TryAddWithoutValidation("Content-Type", "multipart/form-data; boundary=----FLICKR_MIME_20140415120129--");

Once we made this change it all worked correctly.

(Note that this is on WinRT if that makes any difference)