Visual Studio scaffold with error 'Install the package Microsoft.VisualStudio.Web.CodeGeneration.Design and try again.'

.NET 5, latest release Visual Studio, latest release related issue: #1393

To reproduce the problem. In VS

• Create a new Razor Pages web app (5.0)
• Add a model

using System;

namespace ContosoUniversity.Models
{
    public class Student
    {
        public int ID { get; set; }
        public string LastName { get; set; }
        public string FirstMidName { get; set; }
        public DateTime EnrollmentDate { get; set; }
    }
}

Scaffold with model and use + to create a context. The scaffolder adds the following mismatched packages before VS throws an error

  <ItemGroup>
    <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="5.0.4" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="5.0.4">
      <PrivateAssets>all</PrivateAssets>
    <PackageReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Design" Version="5.0.2" />
  </ItemGroup>

Expected result: Scaffolded model.

Actual results:

---

Microsoft Visual Studio

Error

There was an error running the selected code generator:

‘Install the package Microsoft.VisualStudio.Web.CodeGeneration.Design and try again.’

OK

The preceding error results from VS not loading the mismatched NuGet Packages on the first try:

Work around:

Run the scaffolder again. It succeeds the 2nd time.

[cokietech]

I uninstalled and reinstalled Microsoft.VisualStudio.Web.CodeGeneration.Design NuGet package in the package manager. Doing so brought in the CodeGenerator.Design package and added Microsoft.EntityFrameworkCore.Tools. This solved my problem.

Like others, I got the error working through “Get started with Razor Pages in ASP.NET Core” tutorial. The .NET 7 version. I tried several of the above solutions to no avail. I noticed that the project file had a package reference to Microsoft.VisualStudio.Web.CodeGeneration.Design, but it didn’t show up in the project packages. The package showed installed in the Nuget package manager. I uninstalled and reinstalled it in the Nuget package manager. Doing so brought in the CodeGenerator.Design package and added Microsoft.EntityFrameworkCore.Tools. This solved my problem.

[omadawnx]

in my case, making sure all references are latest version 6 (matches the current net version for now), and installing Microsoft.EntityFrameworkCore.Relational did the trick.