Startup failure with rc2-20466 and dotnet rc2-002339

[Tratcher]

From @nil4 on April 10, 2016 22:23

When an exception is thrown in the constructor of a service, and that service is injected in the Configure method, the application crashes on startup, but does not include any trace of the actual exception.

I encountered the issue in a larger project, and reduced the repro to this gist. Versions of Windows, dotnet, dnvm and the content of project.lock.json are also included there. Here is the code:

sealed class Startup {
  public static void Main(string[] args) => new WebHostBuilder().CaptureStartupErrors(false)
    .UseKestrel().UseStartup<Startup>().Build().Run();

  public void ConfigureServices(IServiceCollection services) => services.AddSingleton<Crasher>();

  public void Configure(Crasher crasher) {}
}

sealed class Crasher {
  public Crasher() { throw new Exception("Crash in the constructor"); }
}

Running the repro application with -f net461 prints the following to the console before the Windows error dialog (Repro.exe has stopped working) shows up:

> dotnet run -f net461
Unhandled Exception: System.Exception: Could not resolve a service of type 'Repro.Crasher' for the parameter 'crasher' of method 'Configure' on type 'Repro.Startup'.
   at Microsoft.AspNetCore.Hosting.Startup.ConfigureBuilder.Invoke(Object instance, IApplicationBuilder builder)
   at Microsoft.AspNetCore.Hosting.Internal.WebHost.BuildApplication()
   at Microsoft.AspNetCore.Hosting.WebHostBuilder.Build()
   at Repro.Startup.Main(String[] args)

I expected the actual exception message (Crash in the constructor) and source (Repro.Crasher) to be shown. In the real application, it took a long time to figure out the cause of the crash.

Changing to CaptureStartupErrors(true) prints the same error message, but the application does not crash; it starts listening on http://localhost:5000. However, the startup error page also does not include any details of the actual exception; the only thing it shows is:

Oops. 500 Internal Server Error
An error occurred while starting the application.

Trying to run the same repro with -f netcoreapp1.0 fails with Could not resolve coreclr path. I know things are still in flux with the new TFM, so I thought I should mention this also, just in case I missed something obvious in my project.json.

Copied from original issue: dotnet/aspnetcore#1384

[Tratcher]

From @davidfowl on April 11, 2016 4:22

We're throwing the stack away here

Hosting/src/Microsoft.AspNetCore.Hosting/Startup/ConfigureBuilder.cs

Line 45 in b7bdc9c

throw new Exception(string.Format(

/cc @Tratcher @JunTaoLuo

[nil4]

@davidfowl @Tratcher implementation and test added; care to have another look?