Could not load file or assembly "System.Interactive.Async"

I’m trying to use scaffolding with aspnet-codegenerator but it fails with the following error message: Could not load file or assembly “System.Interactive.Async”

In my console window i write this command:

D:\855 ASP.NET\CMC\src\CMC>dotnet aspnet-codegenerator -p "D:\855 ASP.NET\CMC\src\CMC" controller -name ProjectController -m Project -dc CMC.Models.CMCContext
Building project ...
Finding the generator 'controller'...
Running the generator 'controller'...
Attempting to compile the application in memory
Attempting to figure out the EntityFramework metadata for the model and DbContext: Project
Could not load file or assembly 'System.Interactive.Async, Version=3.0.0.0, Culture=neutral, PublicKeyToken=94bc3704cddfc263'. Das System kann die angegebene Datei nicht finden. StackTrace:
   at Microsoft.EntityFrameworkCore.Infrastructure.EntityFrameworkServiceCollectionExtensions.AddQuery(IServiceCollection serviceCollection)
   at Microsoft.EntityFrameworkCore.Infrastructure.EntityFrameworkServiceCollectionExtensions.AddEntityFramework(IServiceCollection serviceCollection)
   at Microsoft.EntityFrameworkCore.Infrastructure.RelationalServiceCollectionExtensions.AddRelational(IServiceCollection services)
   at Microsoft.Extensions.DependencyInjection.SqlServerServiceCollectionExtensions.AddEntityFrameworkSqlServer(IServiceCollection services)
   at CMC.Startup.ConfigureServices(IServiceCollection services)
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at Microsoft.AspNetCore.Hosting.ConventionBasedStartup.ConfigureServices(IServiceCollection services)
   at Microsoft.AspNetCore.Hosting.Internal.WebHost.EnsureApplicationServices()
   at Microsoft.AspNetCore.Hosting.Internal.WebHost.BuildApplication()
   at Microsoft.AspNetCore.Hosting.WebHostBuilder.Build()
   at Microsoft.VisualStudio.Web.CodeGeneration.EntityFrameworkCore.EntityFrameworkServices.TryCreateContextUsingAppCode(Type dbContextType, ModelType startupType)
Could not load file or assembly 'System.Interactive.Async, Version=3.0.0.0, Culture=neutral, PublicKeyToken=94bc3704cddfc263'. Das System kann die angegebene Datei nicht finden.
   at Microsoft.VisualStudio.Web.CodeGeneration.ActionInvoker.<BuildCommandLine>b__6_0()
   at Microsoft.Extensions.CommandLineUtils.CommandLineApplication.Execute(String[] args)
   at Microsoft.VisualStudio.Web.CodeGeneration.CodeGenCommand.Execute(String[] args)
RunTime 00:00:38.43

If the assembly added with nuget then i also get this error.

My project.json looks like this:

{
  "buildOptions": {
    "emitEntryPoint": true,
    "preserveCompilationContext": true
  },
  "dependencies": {
    "Microsoft.NETCore.App": {
      "type": "platform",
      "version": "1.1.0-*"
    },
    "Microsoft.AspNetCore.Authentication": "1.0.0",
    "Microsoft.AspNetCore.Authorization": "1.1.0-*",
    "Microsoft.AspNetCore.Diagnostics": "1.0.0",
    "Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore": "1.0.0",
    "Microsoft.AspNetCore.Mvc": "1.1.0-*",
    "Microsoft.AspNetCore.Mvc.TagHelpers": "1.1.0-*",
    "Microsoft.AspNetCore.Razor.Tools": "1.0.0-*",
    "Microsoft.AspNetCore.Server.IISIntegration": "1.0.0",
    "Microsoft.AspNetCore.Server.Kestrel": "1.1.0-preview1-final",
    "Microsoft.AspNetCore.StaticFiles": "1.0.0",
    "Microsoft.EntityFrameworkCore": "1.1.0-preview1-final",
    "Microsoft.EntityFrameworkCore.Design": "1.0.1",
    "Microsoft.EntityFrameworkCore.SqlServer": "1.1.0-preview1-final",
    "Microsoft.EntityFrameworkCore.Tools": "1.0.0-*",
    "Microsoft.Extensions.CodeGenerators.Mvc": "1.0.0-rc1-final",
    "Microsoft.Extensions.Logging.Console": "1.0.0",
    "Microsoft.VisualStudio.Web.BrowserLink.Loader": "14.0.0",
    "Microsoft.VisualStudio.Web.CodeGeneration.Tools": "1.0.0-*",
    "Microsoft.VisualStudio.Web.CodeGenerators.Mvc": "1.0.0-preview3-final",
    "System.Interactive.Async": "3.0.0"
  },
  "frameworks": {
    "netcoreapp1.1": {
      "imports": [
        "dotnet5.6",
        "dnxcore50",
        "portable-net45+win8",
        "portable-net45+win8+wp8+wpa81"
      ]
    }
  },
  "publishOptions": {
    "include": [
      "wwwroot",
      "**/*.cshtml",
      "web.config"
    ]
  },
  "runtimeOptions": {
    "configProperties": {
      "System.GC.Server": true
    }
  },
  "scripts": {
    "prepublish": [ "npm install", "bower install", "gulp clean", "gulp min" ],
    "postpublish": [ "dotnet publish-iis --publish-folder %publish:OutputPath% --framework %publish:FullTargetFramework%" ]
  },
  "tools": {
    "Microsoft.AspNetCore.Razor.Tools": "1.0.0-preview3-final",
    "Microsoft.AspNetCore.Server.IISIntegration.Tools": "1.0.0-preview2-final",
    "Microsoft.EntityFrameworkCore.Tools": "1.0.0-preview3-final",
    "Microsoft.VisualStudio.Web.CodeGeneration.Tools": {
      "version": "1.0.0-preview3-final",
      "imports": [ "portable-net45+win8+wp8+wpa81" ]
    }
  }
}

[sfmskywalker]

I’m having this same issue:

It makes sense in my case, since something caused the System.Interactive.Async package to be bumped up to v3.1.1.0, while EF Core clearly is looking for 3.0.0.0.

So for me, this fix is to add an assembly binding in app.config like so:

<dependentAssembly>
    <assemblyIdentity name="System.Interactive.Async" publicKeyToken="94bc3704cddfc263" culture="neutral" />
    <bindingRedirect oldVersion="0.0.0.0-3.0.3000.0" newVersion="3.0.0.0" />
</dependentAssembly>

[Eilon]

Closing because there doesn’t seem to be any further action required on this issue.