Jake Ginnivan's blog

Web Api Problem - 404s for Everything


So the scenario is that we are in the middle of migrating all our services into Azure, and there will be a time when our services will be running on premise and also in Azure.

We added this class to our project and added a reference to Microsoft.WindowsAzure.ServiceRuntime (from the GAC):

public class WebRole : RoleEntryPoint
    public override bool OnStart()
        //Start code
        return base.OnStart();

Our WebApi site starts 404'ing. There was also a heap of other work which was brought in at the same time, so tracking this down was rather hard.

The issue

So I started work this morning investigating why our UI automation tests were all hanging/broken. I noticed our message processor was logging errors ‘Not Found’, restarting everything I managed to get something which looked like:

{"Message":"No HTTP resource was found that matches the request URI 'http://localhost/TestSite/api/values'.","MessageDetail":"No type was found that matches the controller named 'values'."}

Remember that WebRole class we added, well RoleEntryPoint comes from Microsoft.WindowsAzure.ServiceRuntime is referenced from the GAC, and it seems that WebApi reflects over all types in the solution which would have caused a TypeLoadException to be thrown. This apparently causes Web Api to not work at all…. I also have no idea where this issue comes from, as I cannot see an exception at all when debugging.

To Reproduce

  1. Create a new Web API project
  2. Add a new class called MyDbContext, inheriting from DbContext:

    public void MyDbContext : DbContext {}

  3. Change the entity framework dll to CopyLocal=False

F5, and try and hit your api’s.

Any insights as to why this is happening and how to log the error would be awesome….