Error during runtime compilation for Razor views

[brett-1hw]

REPRO:

1. Open Visual Studio 2019
2. Create New ASP.NET CORE Web Application project
3. Select Web Application (Model-View-Controller) option
4. Add package Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation
5. Update ConfigureServices method in Startup.cs:

services.AddMvc().AddRazorRuntimeCompilation();

6. Start debugging project
7. Edit Index.cshtml:

@{
    ViewData["Title"] = "Home Page";
}

<div class="text-center">
    <h1 class="display-4">Welcomeeee</h1>
    <p>Learn about <a href="https://docs.microsoft.com/aspnet/core">building Web apps with ASP.NET Core</a>.</p>
</div>

8. Refresh page to see changes

EXPECTED:

• Razor views recompile and display updates in browser

ACTUAL:

• 500 error displayed: InvalidOperationException: Cannot find reference assembly 'Microsoft.AspNetCore.Antiforgery.dll' file for package Microsoft.AspNetCore.Antiforgery
  

[pranavkm]

@brett-1hw could you try editing your project file to set <PreserveCompilationReferences>true</PreserveCompilationReferences>? I suspect you're running in to the issue I described in #7966 (comment)

[brett-1hw]

Yep, that does indeed fix the problem. I should've specified that I'm running a netcoreapp3.0 project with the latest preview 3 SDK.

[pranavkm]

@brett-1hw I've documented the workaround in our known issues: https://github.com/dotnet/core/blob/master/release-notes/3.0/preview/3.0.0-preview-known-issues.md. We'll use #7966 to track fixing this.