Class library added to a web app not found at runtime

[tmeschter]

Installed VS: d15prerel 26426.1-Preview with the following workloads:

• Universal Windows Platform development
• .NET desktop development
• Desktop development with C++
• ASP.NET and web development
• Office/SharePoint development
• Mobile development with JavaScript
• Visual Studio extension development
• Linux development with C++

Note that VS isn't actually used in this repro, I just used it as a vehicle to get the tools.

Repro Steps

1. Open a new command window (non-admin).
2. mkdir Bug
3. cd Bug
4. dotnet new sln
5. md WebApp
6. cd WebApp
7. dotnet new mvc --framework netcoreapp2.0
8. cd ..
9. md ClassLibrary
10. cd ClassLibrary
11. dotnet new classlib --framework netcoreapp2.0
12. Edit Class1.cs, add the following to the class, and save:

public string GetHello()
{
    return "Hello from class library";
}

13. cd ..\WebApp
14. dotnet add reference ..\ClassLibrary\ClassLibrary.csproj
15. cd ..
16. dotnet sln add WebApp\WebApp.csproj
17. dotnet sln add ClassLibrary\ClassLibrary.csproj
18. cd WebApp
19. Edit Controllers\HomeController.cs and update the About() method to the following, and save:

public IActionResult About()
{
    var c = new ClassLibrary.Class1();
    Console.WriteLine(c.GetHello());
    ViewData["Message"] = c.GetHello();

    return View();
}

20. cd ..
21. dotnet build
22. cd WebApp
23. dotnet run
24. Open a browser and load http://localhost:5000 (or whatever port the web server is listening on).
25. In the banner, click "About".

Expected Behavior

The "About" page includes the "Hello from class library" message.

Actual Behavior

An exception is thrown and the page does not render properly because ClassLibrary1 is not found:

fail: Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware[0]
      An unhandled exception has occurred: Could not load file or assembly 'ClassLibrary, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'. The system cannot find the file specified.
System.IO.FileNotFoundException: Could not load file or assembly 'ClassLibrary, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'. The system cannot find the file specified.
File name: 'ClassLibrary, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'
   at WebApp.Controllers.HomeController.About()
   at lambda_method(Closure , Object , Object[] )
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.<InvokeActionMethodAsync>d__18.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.<InvokeNextActionFilterAsync>d__16.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Rethrow(ActionExecutedContext context)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.<InvokeInnerFilterAsync>d__21.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Mvc.Core.Internal.ResourceInvoker.<InvokeNextResourceFilter>d__18.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at Microsoft.AspNetCore.Mvc.Core.Internal.ResourceInvoker.Rethrow(ResourceExecutedContext context)
   at Microsoft.AspNetCore.Mvc.Core.Internal.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Core.Internal.ResourceInvoker.<InvokeFilterPipelineAsync>d__13.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Mvc.Core.Internal.ResourceInvoker.<InvokeAsync>d__11.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Builder.RouterMiddleware.<Invoke>d__4.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.<Invoke>d__6.MoveNext()

[livarcocc]

I believe you are missing a dotnet restore after adding the reference from the WebApp to the ClassLibrary. I tried this here now and it worked and hitting About display the appropriate message coming from the ClassLibrary.