实体框架影响迁移历史位置的自动迁移

我的自动迁移在尝试更新数据库时一直给我这个错误。

影响迁移位置的自动迁移历史系统表(如默认模式更改)则不是支持。请对影响的操作使用基于代码的迁移迁移历史系统表的位置。

[DbConfigurationType(typeof(AlvinCMSExtension.Migration.AlvinCMSCustomHistoryConfiguration))]
public class AccountDBContext : DbContext
{
    public AccountDBContext()
        : base("DefaultConnection")
    {
        Database.SetInitializer(new MigrateDatabaseToLatestVersion<Alvin_CMS.Models.AccountDBContext, Alvin_CMS.Migrations.AccountDBContext.Configuration>());
    }
    public DbSet<UserProfile> UserProfiles { get; set; }
    public DbSet<Membership> Memberships { get; set; }
    public DbSet<Role> Roles { get; set; }
    public DbSet<UsersInRole> UsersInRoles { get; set; }
    public DbSet<OAuthMembership> OAuthMemberships { get; set; }
    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);
        SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["DefaultConnection"].ToString());
        string query = "select schema_name()";
        if (con.State == ConnectionState.Closed)
            con.Open();
        SqlCommand com = new SqlCommand(query, con);
        var x = com.ExecuteScalar();
        if (con.State == ConnectionState.Open)
            con.Close();
        modelBuilder.HasDefaultSchema(x.ToString());
    }
}
internal sealed class Configuration : DbMigrationsConfiguration<Alvin_CMS.Models.AccountDBContext>
{
    public Configuration()
    {
        AutomaticMigrationsEnabled = true;
        MigrationsDirectory = @"Migrations'AccountDBContext";
        //SetHistoryContextFactory("System.Data.SqlClient", (conn, schema) => new AccountHistoryContext(conn, schema));
    }
    protected override void Seed(Alvin_CMS.Models.AccountDBContext context)
    {
        //  This method will be called after migrating to the latest version.
        //  You can use the DbSet<T>.AddOrUpdate() helper extension method 
        //  to avoid creating duplicate seed data. E.g.
        //
        //    context.People.AddOrUpdate(
        //      p => p.FullName,
        //      new Person { FullName = "Andrew Peters" },
        //      new Person { FullName = "Brice Lambson" },
        //      new Person { FullName = "Rowan Miller" }
        //    );
        //
    }
}
public class CustomHistoryContext : HistoryContext
{
    public CustomHistoryContext(DbConnection dbConnection, string defaultSchema)
        : base(dbConnection, defaultSchema)
    {
    }
    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);
        modelBuilder.HasDefaultSchema("dbo");
        modelBuilder.Entity<HistoryRow>().ToTable(tableName: "__MigrationHistory", schemaName: "dbo");
        //modelBuilder.Entity<HistoryRow>().ToTable(tableName: "__MigrationHistory", schemaName: "dbo");
    }
}
public class AlvinCMSCustomHistoryConfiguration : DbConfiguration
{
    public AlvinCMSCustomHistoryConfiguration()
    {
        this.SetHistoryContext("System.Data.SqlClient",
            (connection, defaultSchema) => new CustomHistoryContext(connection, "dbo"));
    }
}

我可以在没有任何问题的情况下对其他DB上下文进行迁移，但只有在这个AccountDBContext中，错误总是发生。这个错误的原因是什么?