asp.net core and EF core error while add migration

Question

In a asp.net core app, I am trying to to migration for EF code fist.

I got below errors,

An error occurred while calling method 'ConfigureServices' on startup class 'WebAppHandOn.Startup'. Consider using IDbContextFactory to override the initialization of the DbContext at design-time. Error: Could not load file or assembly 'Microsoft.AspNetCore.Routing, Version=1.0.1.0, Culture=neutral, PublicKeyToken=adb9793829ddae60' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)

No parameterless constructor was found on 'ApplicationDbContext'. Either add a parameterless constructor to 'ApplicationDbContext' or add an implementation of 'IDbContextFactory' in the same assembly as 'ApplicationDbContext'.

Here are the different code files,

Startup Class

public void ConfigureServices(IServiceCollection services)
{
    // Add framework services.
    services.AddMvc();

    // Add EntityFramework's Identity support.
    services.AddEntityFramework();

    // Add ApplicationDbContext.
    services.AddDbContext<ApplicationDbContext>(options => options.UseSqlServer(Configuration["Data:DefaultConnection:ConnectionString"]));
}

ApplicationDBContext Class

public class ApplicationDbContext : DbContext {
    #region Constructor

    public ApplicationDbContext(DbContextOptions options) : base(options)
    {
    }
    #endregion Constructor

    #region Methods
    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);
    }
    #endregion Methods

    #region Properties
    public DbSet<Item> Items { get; set; }
    public DbSet<Comment> Comments { get; set; }
    public DbSet<ApplicationUser> Users { get; set; }
    #endregion Properties
}

Project.json Class

 {
      "dependencies": {
     "Microsoft.AspNetCore.Mvc": "1.0.0",
    "Microsoft.AspNetCore.Server.IISIntegration": "1.0.0",
    "Microsoft.AspNetCore.Server.Kestrel": "1.0.0",
    "Microsoft.Extensions.Configuration.EnvironmentVariables": "1.0.0",
    "Microsoft.Extensions.Configuration.FileExtensions": "1.0.0",
    "Microsoft.Extensions.Configuration.Json": "1.0.0",
    "Microsoft.Extensions.Logging": "1.0.0",
    "Microsoft.Extensions.Logging.Console": "1.0.0",
    "Microsoft.Extensions.Logging.Debug": "1.0.0",
    "Microsoft.Extensions.Options.ConfigurationExtensions": "1.0.0",
    "Microsoft.AspNetCore.Diagnostics": "1.0.0",
    "Microsoft.AspNetCore.Routing": "1.0.0",
    "Microsoft.AspNetCore.Authentication.JwtBearer": "1.0.0",
    "Microsoft.AspNetCore.StaticFiles": "1.0.0",
    "Microsoft.VisualStudio.Web.BrowserLink.Loader": "14.0.0",
    "Newtonsoft.Json": "9.0.1",
    "Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore": "1.0.0",
    "Microsoft.AspNetCore.Identity.EntityFrameworkCore": "1.0.0",
    "Microsoft.EntityFrameworkCore": "1.0.0",
    "Microsoft.EntityFrameworkCore.SqlServer": "1.0.0",
    "Microsoft.EntityFrameworkCore.Design": "1.0.0-preview2-final",
    "TinyMapper": "2.0.8"
  },

  "tools": {
    "Microsoft.AspNetCore.Server.IISIntegration.Tools": "1.0.0-preview2-final",
    "Microsoft.EntityFrameworkCore.Tools": "1.0.0-preview2-final"
  },

It is possible that somewhere you are calling new ApplicationDbContext(); Because just at first glance it appears that everything looks right. — Woot
Found this docs.microsoft.com/en-us/ef/core/miscellaneous/cli/dotnet 2/3's they way down they have the solution for this problem — Woot

uche Godfrey uche Godfrey · Accepted Answer · 2017-05-12T20:21:29

Check yourproject.csproj file, remove any preview version in any PackageReference tag and reinstall stable version with manage NuGet packages. Hope that helps

asp.net core and EF core error while add migration

1 Answers