Auto increment is not working on model

I use entity framework core and mysql database.

My model looks like this:

public class User
{
    public int Id { get; set; }
    [Required]
    public string Name { get; set; }
}

When I try to add a user I get Field 'Id' doesn't have a default value

var user = new User {
    Name = "Whatever"
};

_dbContext.Users.Add(user);
_dbContext.SaveChanges(); // Throws exception

And when I debug it I can see that my user's id value is -2147482647

InnerException  {MySql.Data.MySqlClient.MySqlException: Field 'Id' doesn't have a default value
   at MySql.Data.MySqlClient.MySqlDataReader.ActivateResultSet(ResultSet resultSet)
   at MySql.Data.MySqlClient.MySqlDataReader.<ReadFirstResultSetAsync>d__62.MoveNext()

I tried using [DatabaseGenerated(DatabaseGeneratedOption.Identity)] and [Key], but it didn't do anything. My generated migration looks like this:

    [DbContext(typeof(TetrominoContext))]
    [Migration("20170625090637_SixthMigration")]
    partial class SixthMigration
    {
        protected override void BuildTargetModel(ModelBuilder modelBuilder)
        {
            modelBuilder
                .HasAnnotation("ProductVersion", "1.1.2");

            modelBuilder.Entity("Tetromino.Models.User", b =>
                {
                    b.Property<int>("Id")
                        .ValueGeneratedOnAdd();

                    b.Property<string>("Name")
                        .IsRequired();

                    b.HasKey("Id");

                    b.ToTable("Users");
                });
        }
    }

My packages:

  <ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore" Version="1.1.2" />
    <PackageReference Include="Microsoft.AspNetCore.Mvc" Version="1.1.3" />
    <PackageReference Include="Microsoft.AspNetCore.NodeServices" Version="1.1.1" />
    <PackageReference Include="Microsoft.AspNetCore.StaticFiles" Version="1.1.2" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="1.1.2" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="1.1.1" />
    <PackageReference Include="Microsoft.Extensions.Logging.Debug" Version="1.1.2" />
    <PackageReference Include="Microsoft.VisualStudio.Web.BrowserLink" Version="1.1.2" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="1.1.2" />
    <PackageReference Include="Pomelo.EntityFrameworkCore.MySql" Version="1.1.2" />
  </ItemGroup>

After looking at my database it looks like entity framework doesn't set field Id as auto-incremental, but I can't find a way to force it.

I recreated my database to see if it would help, but the error still occurs, so I suspect that I have to modify migration somehow.