Custom Error Handlers throwing 405 for asmx WebService

Question

I've set up a web service (of the .asmx variety) and have ran into an issue when I turn on custom error handling; everything is working fine with custom errors off. When I turn them on and I make the same web service call I get returned a 405 status with the below error:

[HttpException (0x80004005): Request format is unrecognized.]
   System.Web.Services.Protocols.WebServiceHandlerFactory.CoreGetHandler(Type type, HttpContext context, HttpRequest request, HttpResponse response) +489467
   System.Web.Services.Protocols.WebServiceHandlerFactory.GetHandler(HttpContext context, String verb, String url, String filePath) +212
   System.Web.Script.Services.ScriptHandlerFactory.GetHandler(HttpContext context, String requestType, String url, String pathTranslated) +120
   System.Web.MaterializeHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +346
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean&amp; completedSynchronously) +155

My web service declaration is as follows and it's being called through javascript as a POST to http://xxx/WebServices/TestService.asmx/MyMethod with param1=xyz in the body.

namespace Website.WebServices
{
    [WebService(Namespace = "http://tempuri.org/")]
    [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
    [System.ComponentModel.ToolboxItem(false)]
    [System.Web.Script.Services.ScriptService]
    public class TestService : System.Web.Services.WebService
    {
        [WebMethod(EnableSession = true)]
        [ScriptMethod(UseHttpGet = false, ResponseFormat = ResponseFormat.Json)]
        public void MyMethod(string param1)
        {
            //...Do some important stuff
        }
    }
}

For completeness my declaration in the Web.Config is below:

<system.webServer>
...
<httpErrors  errorMode="Custom" existingResponse="Replace">
    <remove statusCode="404" subStatusCode="-1"/>
    <error statusCode="404" path="/Error404.aspx" responseMode="ExecuteURL"/>
    <remove statusCode="500" subStatusCode="-1"/>
    <error statusCode="500" path="/Error.aspx" responseMode="ExecuteURL"/>
</httpErrors>
...
</system.webServer>

Following this through in the Application_BeginRequest global function I can see that everything is coming in fine - I just can't see where it could be going wrong! I've also gone directly to the asmx file and submitted via the generated form and receive the same error.

This has been tested, and is doing the same thing, on an IIS7 machine as well as my IIS express dev machine.

Richard Ockerby Richard Ockerby · Accepted Answer · 2015-08-13T13:09:47

Managed to resolve this issue by changing the existingResponse to Auto (kudos to Merk for his answer Response.TrySkipIisCustomErrors not working).

My understanding from this is that you have your two types of response for errors; Replace and PassThrough. PassThrough gives back exactly what the .NET generates (skipping IIS errors) and Replace replaces the response with whatever you have defined within the for that code. As I had this set to Replace it was scrapping my WebService response and replacing it with the custom one which, due to the runAllManagedModulesForAllRequests flag being set to true, attempted to re-run the webservice call but without a request body - hence the original error of 405 as the param1 was missing.

Hope this helps someone else save a day's worth of investigation!

Custom Error Handlers throwing 405 for asmx WebService

1 Answers