Unable to access Topic Map tab when using a remote server

Symptoms

The Topic Map tab fails to load correctly and in the client trace you see the message:

FATAL - Javascript Error http://.../ui/edit/EditPanel.aspx?id=453:306 'TopicType' is null or not an object

The stack trace showing:

System.InvalidOperationException: Request format is unrecognized for URL unexpectedly ending in '/GetTopicNameAndType'.

   at System.Web.Services.Protocols.WebServiceHandlerFactory.CoreGetHandler(Type type, HttpContext context, HttpRequest request, HttpResponse response)

   at System.Web.Services.Protocols.WebServiceHandlerFactory.GetHandler(HttpContext context, String verb, String url, String filePath)

   at System.Web.Script.Services.ScriptHandlerFactory.GetHandler(HttpContext context, String requestType, String url, String pathTranslated)

   at System.Web.HttpApplication.MapHttpHandler(HttpContext context, String requestType, VirtualPath path, String pathTranslated, Boolean useAppConfig)

   at System.Web.HttpApplication.MapHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()

   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

Fix

The most common cause of this is that the EPiServer web application is not configured to accept HTTP POST requests from remote hosts. This can be fixed by adding the following declaration to the EPiServer application's web.config, under the main configuration element of the file:

<location path="NetworkedPlanet/EPiServerModule/Service/TMCoreEPiDataService.asmx">

  <system.web>

    <webServices>

      <protocols>

        <add name="HttpPost"/>

      </protocols>

    </webServices>

  </system.web>

</location>

You may need to change the value of the path attribute if you have installed the TMCore EPiServer Module services in a different location on the site.