dotnet build - get error "could not return the default page '/index.html'"

Question

try to generate my project into exe file, but get error:

before: "dotnet build -r win10-x86" is ok

after run generated exe, all is ok also:

indows DPAPI to encrypt keys at rest.
Hosting environment: Production
Content root path: C:....\currencyColution\correncyProject\bin\Debug\netcoreapp2.1\win10-x86
Now listening on: http://localhost:5000
Now listening on: https://localhost:5001
Application started. Press Ctrl+C to shut down.

after load page is somwthing worng, more precisely index.html is not found:

info: Microsoft.AspNetCore.Hosting.Internal.WebHost[1]
      Request starting HTTP/1.1 GET http://localhost:5000/
fail: Microsoft.AspNetCore.Server.Kestrel[13]
      Connection id "0HLG91TC2H0UO", Request id "0HLG91TC2H0UO:00000001": An 

unhandled exception was thrown by the application.
System.InvalidOperationException: The SPA default page middleware could not return the default page '/index.html' because it was not found, and no other middleware handled the request.
Your application is running in Production mode, so make sure it has been published, or that you have built your SPA manually. Alternatively you may wish to switch to the Development environment.

Startup.cs

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.SpaServices.AngularCli;
using Microsoft.Extensions.DependencyInjection;
using Swashbuckle.AspNetCore.Swagger;
using System;
using System.IO;
using Microsoft.AspNetCore.Http;

namespace AspNetCore2Ang6Template
{
  public class Startup
  {
  
    public void ConfigureServices(IServiceCollection services)
    {
      services.AddMvc();
      services.AddSpaStaticFiles(c =>
      {
        c.RootPath = "wwwroot";
      });

    }

    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
      if (env.IsDevelopment())
      {
        app.UseDeveloperExceptionPage();
      }

      app.UseDefaultFiles();
      app.UseStaticFiles();
      app.UseSpaStaticFiles();
      app.UseMvc(routes =>
      {
        routes.MapRoute(name: "default", template: "{controller}/{action=index}/{id}");
      });

      app.UseSpa(spa =>
      {
        spa.Options.SourcePath = "wwwroot";
      });

    }
  }
}

I dont't use angular and some other ones, just try to open wwwroot/index.html

files:

currencyProject

wwwroot

Program.cs

Startup.cs

Tested in VS , all works, but not via exe builder

launched like dev : dotnet run, then it works on localhost:58893/, but what is wrong with prod dotnet build on localhost:5000

launchSettings:

{
  "iisSettings": {
    "windowsAuthentication": false,
    "anonymousAuthentication": true,
    "iisExpress": {
      "applicationUrl": "http://localhost:58842/",
      "sslPort": 0
    }
  },
  "profiles": {
    "IIS Express": {
      "commandName": "IISExpress",
      "launchBrowser": true,
      "environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "Development"
      }
    },
    "AspNetCore2Ang6Template": {
      "commandName": "Project",
      "launchBrowser": true,
      "environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "Development"
      },
      "applicationUrl": "http://localhost:58893/"
    }
  }
}

Answer 1

The problem come from the fact when you build the project with the command dotnet build, the wwwroot folder is not copied.

I reproduced your problem, to fix it, I copied the folder in the output and it worked.

You should use the publish command to test production.

In either cases, both commands don't copy the wwwroot folder.