Upgrade from .NET6 to .NET8 throws exception during migration

[Soundman32]

Same issue as this #1823

Looking at the other issue, it was related to guid, which my migration doesn't contain. There are previous migrations that work correctly, but it always fails on this one.

Steps to reproduce

Upgraded from .NET6 to .NET8. Everything is latest.

Pomelo.EntityFrameworkCore.MySql 8.0.2
Microsoft.EntityFrameworkCore 8.0.7

Migration up method:

        protected override void Up(MigrationBuilder migrationBuilder)
        {
            migrationBuilder.CreateTable(
                name: "granular_average",
                columns: table => new
                {
                    granularAverageId = table.Column<int>(type: "int", nullable: false)
                        .Annotation("MySql:ValueGenerationStrategy", MySqlValueGenerationStrategy.IdentityColumn),
                    activityId = table.Column<int>(type: "int", nullable: false),
                    activityMetricId = table.Column<int>(type: "int", nullable: false),
                    concurrencyToken = table.Column<DateTime>(type: "timestamp(6)", rowVersion: true, nullable: true),
                    count = table.Column<int>(type: "int", nullable: false, defaultValue: 0),
                    countryCode = table.Column<string>(type: "longtext", nullable: true)
                        .Annotation("MySql:CharSet", "utf8mb4"),
                    gender = table.Column<string>(type: "longtext", nullable: true)
                        .Annotation("MySql:CharSet", "utf8mb4"),
                    name = table.Column<string>(type: "varchar(255)", nullable: false)
                        .Annotation("MySql:CharSet", "utf8mb4"),
                    scale = table.Column<int>(type: "int", nullable: false),
                    total = table.Column<string>(type: "longtext", nullable: false, defaultValue: "AA==")
                        .Annotation("MySql:CharSet", "utf8mb4"),
                    yearsExperience = table.Column<int>(type: "int", nullable: true)
                },
                constraints: table =>
                {
                    table.PrimaryKey("pk-granular_average", x => x.granularAverageId);
                    table.ForeignKey(
                        name: "fk-granular_average-activity",
                        column: x => x.activityId,
                        principalTable: "activity",
                        principalColumn: "activityId",
                        onDelete: ReferentialAction.Cascade);
                    table.ForeignKey(
                        name: "fk-granular_average-activityMetric",
                        column: x => x.activityMetricId,
                        principalTable: "activity_metric",
                        principalColumn: "activityMetricId",
                        onDelete: ReferentialAction.Cascade);
                })
                .Annotation("MySql:CharSet", "utf8mb4");

            migrationBuilder.CreateIndex(
                name: "ix-granular_average-activityId",
                table: "granular_average",
                column: "activityId");

            migrationBuilder.CreateIndex(
                name: "ix-granular_average-activityMetricId",
                table: "granular_average",
                column: "activityMetricId");

            migrationBuilder.CreateIndex(
                name: "ix-granular_average-name",
                table: "granular_average",
                column: "name",
                unique: true);
        }

The issue

Exception thrown: 'System.NullReferenceException' in Microsoft.EntityFrameworkCore.Relational.dll

  Error Message:
   System.NullReferenceException : Object reference not set to an instance of an object.
  Stack Trace:
     at Microsoft.EntityFrameworkCore.Storage.RelationalTypeMappingSource.FindCollectionMapping(RelationalTypeMappingInfo info, Type modelType, Type providerType, CoreTypeMapping elementMapping)
   at Microsoft.EntityFrameworkCore.Storage.RelationalTypeMappingSource.<>c.<FindMappingWithConversion>b__8_0(ValueTuple`4 k, RelationalTypeMappingSource self)
   at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd[TArg](TKey key, Func`3 valueFactory, TArg factoryArgument)
   at Microsoft.EntityFrameworkCore.Storage.RelationalTypeMappingSource.FindMappingWithConversion(RelationalTypeMappingInfo mappingInfo, Type providerClrType, ValueConverter customConverter)
   at Microsoft.EntityFrameworkCore.Storage.RelationalTypeMappingSource.FindMappingWithConversion(RelationalTypeMappingInfo mappingInfo, IReadOnlyList`1 principals)
   at Microsoft.EntityFrameworkCore.Storage.RelationalTypeMappingSource.FindMapping(IProperty property)
   at Microsoft.EntityFrameworkCore.Metadata.Internal.Property.<>c.<get_TypeMapping>b__94_0(IProperty property)
   at Microsoft.EntityFrameworkCore.Internal.NonCapturingLazyInitializer.EnsureInitialized[TParam,TValue](TValue& target, TParam param, Func`2 valueFactory)
   at Microsoft.EntityFrameworkCore.Metadata.Internal.Property.get_TypeMapping()
   at Microsoft.EntityFrameworkCore.Metadata.Internal.Property.Microsoft.EntityFrameworkCore.Metadata.IReadOnlyProperty.FindTypeMapping()
   at Microsoft.EntityFrameworkCore.RelationalPropertyExtensions.FindRelationalTypeMapping(IReadOnlyProperty property)
   at Microsoft.EntityFrameworkCore.RelationalPropertyExtensions.GetColumnType(IReadOnlyProperty property)
   at Microsoft.EntityFrameworkCore.RelationalPropertyExtensions.GetColumnType(IProperty property)
   at Microsoft.EntityFrameworkCore.Metadata.Internal.RelationalModel.CreateDefaultColumnMapping(ITypeBase typeBase, ITypeBase mappedType, TableBase defaultTable, TableMappingBase`1 tableMapping, Boolean isTph, Boolean isTpc)
   at Microsoft.EntityFrameworkCore.Metadata.Internal.RelationalModel.AddDefaultMappings(RelationalModel databaseModel, IEntityType entityType, IRelationalTypeMappingSource relationalTypeMappingSource)
   at Microsoft.EntityFrameworkCore.Metadata.Internal.RelationalModel.Create(IModel model, IRelationalAnnotationProvider relationalAnnotationProvider, IRelationalTypeMappingSource relationalTypeMappingSource, Boolean designTime)
   at Microsoft.EntityFrameworkCore.Metadata.Internal.RelationalModel.Add(IModel model, IRelationalAnnotationProvider relationalAnnotationProvider, IRelationalTypeMappingSource relationalTypeMappingSource, Boolean designTime)
   at Microsoft.EntityFrameworkCore.Infrastructure.RelationalModelRuntimeInitializer.InitializeModel(IModel model, Boolean designTime, Boolean prevalidation)
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelRuntimeInitializer.Initialize(IModel model, Boolean designTime, IDiagnosticsLogger`1 validationLogger)
   at Microsoft.EntityFrameworkCore.Migrations.Internal.Migrator.FinalizeModel(IModel model)
   at Microsoft.EntityFrameworkCore.Migrations.Internal.Migrator.GenerateUpSql(Migration migration, MigrationsSqlGenerationOptions options)
   at Pomelo.EntityFrameworkCore.MySql.Migrations.Internal.MySqlMigrator.GenerateUpSql(Migration migration, MigrationsSqlGenerationOptions options)
   at Microsoft.EntityFrameworkCore.Migrations.Internal.Migrator.<>c__DisplayClass16_2.<GetMigrationCommandLists>b__2()
   at Microsoft.EntityFrameworkCore.Migrations.Internal.Migrator.Migrate(String targetMigration)
   at Microsoft.EntityFrameworkCore.RelationalDatabaseFacadeExtensions.Migrate(DatabaseFacade databaseFacade)

Further technical details

MySQL version: 8.2.0
Operating system: Windows
Pomelo.EntityFrameworkCore.MySql version: 8.0.2
Microsoft.AspNetCore.App version: 8.0

[Soundman32]

Ha ha, I've been Googling this error for the last couple of days, and I'd forgotten I'd posted this. It's still an issue, even when using the latest .Net8 nugets (8.0.10). I wonder if it's a problem with Pomelo?