It looks as if the web service fails to provide a Content-Type header, but the client expects one.

I'm not the original Anonymous Monk, but will respond: I would have thought the same thing, except that the error message is included in the message, and appears to be showing the content that the client received. That message shows not one but two Content-Type headers. If the error message isn't showing what was received from the service, but some other content, I would be confused as a user of that client.

I'm wondering if seeing two Content-Type headers instead of one-and-only-one is confusing the client. Or maybe the headers don't have the expected newline sequence, so it shows up when printed as being on multiple lines, but the client either sees it as one line or sees extra characters at the start or end of each of the header lines.

(edit first paragraph for clarity)