How do I fix a “Request format is unrecognized for URL…” error in a web service running in IIS?

Question

I am get the following error while running web service in IIS:

Server Error in \'/Inbox Sevice\' Application. Request format is unrecognized for U

Answer 1

Just out of interest (- in the case of accessing the web-service via AJAX); I've found that if a 'content-type' header is not passed (- even if it's a local/"HttpPostLocalhost" request), then the issue occurs, so I pass the header myself (- e.g. via jQuery's '$.ajax()' method rather than without via jQuery's '$.getJSON()' method), instead of resorting to this:

https://support.microsoft.com/en-us/kb/819267