Could not create type '<WebServiceType>' at System.Web.UI.SimpleWebHandlerParser.GetType(String typeName)
I got this error when trying to view the WSDL, and to access the web service via AJAX. The issue turned out to be easy; the type name in the ASMX file didn't match the full name of the class. I switched folders for this object, so I created it in a different folder, without changing the @WebService directive. So Visual Studio doesn't rename the paths whenever the folders change, and thus a manual change is required in the code-behind file and the @WebService directive.