WCF Service Returning "Method Not Allowed"

If you are using the [WebInvoke(Method="GET")] attribute on the service method, make sure that you spell the method name as "GET" and not "Get" or "get" since it is case sensitive! I had the same error and it took me an hour to figure that one out.

Your browser is sending an HTTP GET request: Make sure you have the WebGet attribute on the operation in the contract:

[ServiceContract]
public interface IUploadService
{
    [WebGet()]
    [OperationContract]
    string TestGetMethod(); // This method takes no arguments, returns a string. Perfect for testing quickly with a browser.

    [OperationContract]
    void UploadFile(UploadedFile file); // This probably involves an HTTP POST request. Not so easy for a quick browser test.
 }