Can't add empty or new migration with Add-Migration

[Monsieur-Ours]

trafficstars

Steps to reproduce

• Have already a migration
• Try to add another one by just using Package Manager Console command => Add-Migration Test
• Or try to add an empty migration

The issue

Supposed to add an empty or a new migration with all it's script to update my database.

If you are seeing an exception, include the full exceptions details (message and stack trace).

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.InitializeColumnHelper(ColumnOperation columnOperation, IColumn column, Boolean inline)
   at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.Diff(IColumn source, IColumn target, DiffContext diffContext)+MoveNext()
   at Pomelo.EntityFrameworkCore.MySql.Migrations.Internal.MySqlMigrationsModelDiffer.MakeStringColumnsRequiredWithoutUnexpectedDefaultValue(IColumn source, IColumn target, IEnumerable`1 migrationOperations)+MoveNext()
   at Pomelo.EntityFrameworkCore.MySql.Migrations.Internal.MySqlMigrationsModelDiffer.SkipRedundantCharSetSpecifyingAlterColumnOperations(IEnumerable`1 migrationOperations)+MoveNext()
   at Pomelo.EntityFrameworkCore.MySql.Migrations.Internal.MySqlMigrationsModelDiffer.PostFilterOperations(IEnumerable`1 migrationOperations)+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 Pomelo.EntityFrameworkCore.MySql.Migrations.Internal.MySqlMigrationsModelDiffer.PostFilterOperations(IEnumerable`1 migrationOperations)+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 Pomelo.EntityFrameworkCore.MySql.Migrations.Internal.MySqlMigrationsModelDiffer.PostFilterOperations(IEnumerable`1 migrationOperations)+MoveNext()
   at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.Sort(IEnumerable`1 operations, DiffContext diffContext)
   at Pomelo.EntityFrameworkCore.MySql.Migrations.Internal.MySqlMigrationsModelDiffer.Sort(IEnumerable`1 operations, DiffContext diffContext)
   at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.GetDifferences(IRelationalModel source, IRelationalModel target)
   at Pomelo.EntityFrameworkCore.MySql.Migrations.Internal.MySqlMigrationsModelDiffer.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.

Further technical details

MySQL version: 8.0.32 MySQL Community Server Operating system: Windows 10 22H2 Pomelo.EntityFrameworkCore.MySql version: 7.0.0 Microsoft.AspNetCore.App version: 6.0

[JohannSig]

Have you tried running it with the -Verbose flag? You can see the log trace for what EF is doing and figure out where its stranding.

[Monsieur-Ours]

Have you tried running it with the -Verbose flag? You can see the log trace for what EF is doing and figure out where its stranding.

Hey ! Yes already and nothing seems to appear clearly. The probelm might come from the package as I'm able to do it with Oracle one.

[Soundman32]

I have this too. Previous migration is created without a problem, but if I immediately add another migration (with zero change), then this exception is thrown.

[Soundman32]

I tried with -verbose and got this:

No application service provider was found. Finding DbContext classes in the project... Found DbContext 'ApplicationDbContext'. Using DbContext factory 'DesignTimeDbContextFactory'. Using context 'ApplicationDbContext'. Finding design-time services referenced by assembly 'XXXX'... Finding design-time services referenced by assembly 'XXXX.Infrastructure'... No referenced design-time services were found. Finding design-time services for provider 'Pomelo.EntityFrameworkCore.MySql'... Using design-time services from provider 'Pomelo.EntityFrameworkCore.MySql'. Finding IDesignTimeServices implementations in assembly 'XXXX'... No design-time services were found. 'ApplicationDbContext' disposed. System.NullReferenceException: Object reference not set to an instance of an object.

[Soundman32]

I think I've found the problem.

I changed my code from:

        builder.Property(p => p.ConcurrencyToken)
            .HasColumnName("concurrencyToken");

to

        builder.Property(p => p.ConcurrencyToken)
            .IsRowVersion()
            .HasColumnName("concurrencyToken");

And then I can no longer create any migrations AFTER the one that created this:

    protected override void Up(MigrationBuilder migrationBuilder)
    {
        migrationBuilder.AlterColumn<byte[]>(
            name: "concurrencyToken",
            table: "my_table",
            type: "timestamp(6)",
            rowVersion: true,
            nullable: true,
            oldClrType: typeof(byte[]),
            oldType: "longblob",
            oldNullable: true);
    }

[Soundman32]

More info:

My concurrency token type was byte[]. This generated a migration that failed when looking up the mapping type.

I changed my concurrency token to DateTime, and it all works now.

[lauxjpn]

This issue should be fixed by https://github.com/PomeloFoundation/Pomelo.EntityFrameworkCore.MySql/pull/1857 (which we have backported to 8.0.2 with #1869).