Can not make a Entity code-first migration at designtime

Question

Can not make a Entity code-first migration at designtime

Jørgen Vig Jensen 0

I would like to run add-migration at design-time on a simple C# application.

Model:

    [Table("Feature")]
    public class Feature
    {
        public int Id { get; set; }
        public string? Priceclass { get; set; }
        public decimal Price { get; set; }
    }

DbContext:

    public class LivfakDbContext : DbContext
    {
        internal DbSet<Feature> Features { get; set; }
        public LivfakDbContext(DbContextOptions<LivfakDbContext> options) : base(options)
        {
        }
        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            optionsBuilder.UseSqlite("Filename=livfakDB.db");
        }
        }
    }

IDesignTimeDbContextFactory:

    public class LivfakDbContextFactory : IDesignTimeDbContextFactory<LivfakDbContext>
    {

        LivfakDbContext IDesignTimeDbContextFactory<LivfakDbContext>.CreateDbContext(string[] args)
        {
            var optionsBuilder = new DbContextOptionsBuilder<LivfakDbContext>();
            optionsBuilder.UseSqlite("Filename=livfakDB.db");

            return new LivfakDbContext(optionsBuilder.Options);
        }

    }

When I run the add-migration command., it throws this exception:

Unable to create a 'DbContext' of type 'RuntimeType'. The exception 'The type initializer for '<Module>' threw an exception.' was thrown while attempting to create an instance.

As I can read, I have to use the IDesignTimeDbContextFactory when I want to migrate at design-time. But I cant see what I miss.

2 answers

Your answer

Answer 1

The occurrence of this kind of problem typically indicates an issue with the configuration or registration of your DbContext in Entity Framework Core.

Example

public class MyDbContext : DbContext
{
   public MyDbContext(DbContextOptions<MyDbContext> options) : base(options) { }
   public MyDbContext() { }
   public DbSet<User> Users { get; set; }
}

Common Causes and Solutions

1. Missing Parameterless Constructor

Ensure your DbContext class has a parameterless constructor.

public MyDbContext() { }

2. Incorrect Service Registration

Make sure your DbContext is correctly registered in the Startup.cs or Program.cs.

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddDbContext<MyDbContext>(options =>
options.UseSqlServer(builder.Configuration.GetConnectionString("DefaultConnection")));

3. Multiple Startup Projects

If you have multiple startup projects, specify the correct project when running migrations.

dotnet ef migrations add InitialCreate --project YourDbContextProject --startup-project YourStartupProject

4. Using IDesignTimeDbContextFactory

Implementing IDesignTimeDbContextFactory can help resolve design-time issues.

public class DesignTimeDbContextFactory : IDesignTimeDbContextFactory<MyDbContext>
{
   public MyDbContext CreateDbContext(string[] args)
  {
     var optionsBuilder = new DbContextOptionsBuilder<MyDbContext>();
     optionsBuilder.UseSqlServer("YourConnectionString");
 
     return new MyDbContext(optionsBuilder.Options);
  }
}

By following these steps, you can resolve the issue and successfully create and use your DbContext in Entity Framework Core

Jørgen Vig Jensen 0 Reputation points

2025-10-21T19:47:10.52+00:00

Sorry, I should have been more specific in my question. I want to create a simple windows application based on the WinUI Blank (Packaged) template. Now I start creating a blank application, just to dig into what the problem is, since I have made a simple console-application where the migration to a SQLite database worked fine.

The WinUI (Packaged) template contains the microsoft.windows.sdk.buildtools package which adds the <EnableMsixTooling>true</EnableMsixTooling> tag

When I try to run the command:

dotnet ef migration add firstmigration I get a build error which turns out to be:

Microsoft.Windows.SDK.BuildTools.MSIX.Packaging.targets(3866,5): error : Packaged .NET applications with an app host exe cannot be ProcessorArchitecture neutral. Please specify a RuntimeIdentifier or a Platform other than AnyCPU.

My project file contains the following configuration:

<PropertyGroup> <OutputType>WinExe</OutputType> <TargetFramework>net8.0-windows10.0.19041.0</TargetFramework> <TargetPlatformMinVersion>10.0.17763.0</TargetPlatformMinVersion> <RootNamespace>WinUIApp</RootNamespace> <ApplicationManifest>app.manifest</ApplicationManifest>  <Platforms>x64</Platforms>  <RuntimeIdentifiers>win-x64</RuntimeIdentifiers> <PublishProfile>win-$(Platform).pubxml</PublishProfile> <UseWinUI>true</UseWinUI> <EnableMsixTooling>true</EnableMsixTooling> <Nullable>enable</Nullable> </PropertyGroup>

You can see that I have tried changing the platform and runtimeidentifier settings.

So I think it has something to do with not being able to run a dotnet ef migration on a packaged WinUI application. Is this correct? and is it possible?

Or is there any way I can create a WinUI application, where I can use the migration-feature ?

Answer 2

Thank you for reaching out.

This happens because WinUI packaged apps use MSIX tooling, which enforces platform-specific build requirements. When you run dotnet ef migrations add, EF Core tries to build the startup project to locate your DbContext. That build triggers MSIX packaging targets, which expect a defined RuntimeIdentifier and platform (like x64 or ARM64) and do not allow AnyCPU. The EF CLI doesn’t provide those settings during design-time, so the build fails. Essentially, EF migrations assume a normal .NET project, but MSIX adds extra constraints that break the process.

Create a Separate Migration Project (Recommended)

Add a new Class Library or Console App to your solution.
Move your DbContext and IDesignTimeDbContextFactory into this project.
Install EF Core packages (Microsoft.EntityFrameworkCore, Microsoft.EntityFrameworkCore.Sqlite).
Run:dotnet ef migrations add InitialCreate --project YourEfProject --startup-project YourEfProject
Reference this EF project in your WinUI app.

Temporarily Disable MSIX Tooling

Edit your WinUI .csproj and set:<EnableMsixTooling>false</EnableMsixTooling>
Run: dotnet ef migrations add InitialCreate
Re-enable MSIX tooling after migration.

Use --no-build

Build your project manually first: dotnet build
Run migration without building: dotnet ef migrations add InitialCreate --no-build

Specify Runtime Identifier

Add this to .csproj: <RuntimeIdentifiers>win-x64</RuntimeIdentifiers>
Run: dotnet ef migrations add InitialCreate --runtime win-x64

Please let us know if you require any further assistance we’re happy to help.

If you found this information useful, kindly mark this as "Accept Answer".

Omkara Varshitha Kunapalli (INFOSYS LIMITED) 1,350 Reputation points Microsoft External Staff

2025-10-24T04:19:05.7066667+00:00

"Hope you're doing well. We're following up on the ticket. Please let us know whether the issue persists or has been resolved. If the issue has been resolved, kindly mark the response as answered"

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Can not make a Entity code-first migration at designtime

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