Naming a migration "DateTimeOffset" doesn't work

Hi,

we added a migration that alters a property type from DateTime to DateTimeOffset. The Migration itself looks as follows:

    public partial class DateTimeOffset : Migration
    {
        protected override void Up(MigrationBuilder migrationBuilder)
        {
            migrationBuilder.AlterColumn<DateTimeOffset>(
                name: "LastModified",
                schema: "dbo",
                table: "Test",
                type: "datetimeoffset",
                nullable: false,
                oldClrType: typeof(DateTime),
                oldType: "datetime2");
        }

        protected override void Down(MigrationBuilder migrationBuilder)
        {
            migrationBuilder.AlterColumn<DateTime>(
                name: "LastModified",
                schema: "dbo",
                table: "Test",
                type: "datetime2",
                nullable: false,
                oldClrType: typeof(DateTimeOffset),
                oldType: "datetimeoffset");
        }
    }

Unfortunately, after this migration is created, calls to dotnet ef migrations add fail with the following exception:

System.NullReferenceException: Object reference not set to an instance of an object.
   at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.Initialize(ColumnOperation columnOperation, IColumn column, RelationalTypeMapping typeMapping, Boolean isNullable, IEnumerable`1 migrationsAnnotations, Boolean inline)
   at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.Diff(IColumn source, IColumn target, DiffContext diffContext)+MoveNext()
   at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.DiffCollection[T](IEnumerable`1 sources, IEnumerable`1 targets, DiffContext diffContext, Func`4 diff, Func`3 add, Func`3 remove, Func`4[] predicates)+MoveNext()
   at System.Linq.Enumerable.ConcatIterator`1.MoveNext()
   at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.Diff(ITable source, ITable target, DiffContext diffContext)+MoveNext()
   at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.DiffCollection[T](IEnumerable`1 sources, IEnumerable`1 targets, DiffContext diffContext, Func`4 diff, Func`3 add, Func`3 remove, Func`4[] predicates)+MoveNext()
   at System.Linq.Enumerable.ConcatIterator`1.MoveNext()
   at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.Sort(IEnumerable`1 operations, DiffContext diffContext)
   at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.GetDifferences(IRelationalModel source, IRelationalModel target)
   at Microsoft.EntityFrameworkCore.Migrations.Design.MigrationsScaffolder.ScaffoldMigration(String migrationName, String rootNamespace, String subNamespace, String language)
   at Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.AddMigration(String name, String outputDir, String contextType, String namespace)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigrationImpl(String name, String outputDir, String contextType, String namespace)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigration.<>c__DisplayClass0_0.<.ctor>b__0()
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.<>c__DisplayClass3_0`1.<Execute>b__0()
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)
Object reference not set to an instance of an object.

We were also able to reproduce that issue in a sample project that only contains an inital migration that creates the table and adds a column for a property of type DateTime and the migration shown above,

We used ef version 5.0.7 to create the migrations

                     _/\__
               ---==/    \\
         ___  ___   |.    \|\
        | __|| __|  |  )   \\\
        | _| | _|   \_/ |  //|\\
        |___||_|       /   \\\/\\

Entity Framework Core .NET Command-line Tools 5.0.7

Could you help us solve our issue? Is something wrong with our migration?

Kind regards, Manuel Gutekunst

[roji]

Triage discussion - if we see other people hitting this, we may add something to the type name for the migration (e.g. the timestamp, like we already do in the file name).

[mgutekunst]

oh…

thanks for claryfying @roji . Renaming the Migrations class solved our issue.