Problem

When attempting to call web services using POST or GET requests (instead of using SOAP), the server rejects all web service calls with a System.Net.WebException message.

Cause

By default, web service requests are not permitted through HTTP POST or HTTP GET.  To enable calling of web services in this way (instead of using SOAP), refer to the following article: http://support.microsoft.com/default.aspx?scid=kb;en-us;819267. 

Solution

Open the web.config file using NotePad, and add the following section inside the <system.web> block:

    <!-- This section sets the .NET Framework settings. -->
    <webServices>
       <protocols>
       <add name="HttpGet"/>
       <add name="HttpPost"/>
       </protocols>
    </webServices>