400.0 Bad Request on REST API on Azure Web Site - asp.net

Question

I have migrated a REST service to an Azure web site, but it keeps coming back with a 400.0 Bad Request error (error code zero).
The service works locally, and works perfectly when running in a Web Role. After moving into a Web Site, it started coming back with the 400.0 error.
My web.config:
<system.webServer>
<modules runAllManagedModulesForAllRequests="true">
<add name="UrlRoutingModule" type="System.Web.Routing.UrlRoutingModule, System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
</modules>
</system.webServer>
<system.serviceModel>
<serviceHostingEnvironment aspNetCompatibilityEnabled="true" />
<standardEndpoints>
<webHttpEndpoint>
<standardEndpoint name="" helpEnabled="true" automaticFormatSelectionEnabled="false" />
</webHttpEndpoint>
</standardEndpoints>
</system.serviceModel>
I already have ASP.NET compatibility set in my class:
[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Required)]
[ServiceBehavior(InstanceContextMode = InstanceContextMode.PerSession, ConcurrencyMode = ConcurrencyMode.Multiple)]
public class BookingService { ... }
and the proper routing defined in Global.asax.cs:
private void Application_Start (object sender, EventArgs e) {
RouteTable.Routes.Add(new ServiceRoute("booking/service", new WebServiceHostFactory(), typeof(BookingService)));
}
Now when I try to access the REST API locally, it works fine:
http://localhost/booking/service/help
However, after uploading the web service into an Azure Web Site and doing:
http://xxx.azurewebsites.net/booking/service/help
it came back with a 400.0 Bad Request. Detailed error logs show:
Request: ManagedPipelineHandler
Notification: ExecuteRequestHandler
Handler: System.ServiceModel.Activation.AspNetRouteServiceHttpHandler
Error code: 0x00000000
I am at a total lost. Googling the web didn't yield anything helpful. I tried putting the following into web.config:
<handlers>
<add name="UrlRoutingHandler" preCondition="integratedMode" verb="*" path="UrlRouting.axd" type="Foo.RoutingHandler" />
</handlers>
and defining a handler by extending UrlRoutingHandler and defining VerifyAndProcessRequest but it still doesn't work.

Answer 1

Finally found the error after stripping the service off bit by bit.
What happened was:
RouteTable.Routes.Add adds a route that creates an object of class BookingService as the handler
The class BookingService has a static property that is initialized
This initialization statement failed (due to some reason not to mention here)
Therefore, when the routing service tries to create a BookingService class, the class's static initializers were first run and failed
As a result, the code never reached the routing service, and so the service failed at the AspNetRouteServiceHttpHandler handler
If the class failed not while running static initializers, but during object creation, it is likely that the routing service will then throw a more meaningful error pin-pointing the problem
In summary, if you see a routed request failing at the handler, it may be caused by class code that couldn't load (due to static initializers failing or some other reason).