title: aspnet - Failure when adding migration: Value cannot be null, parameter name: property
body: <p>i already looking in the web for this error and i cant find any usefull. i tried to create database with entity framework in dotnet but i got this error. any suggestion what i am doing wrong? i would like to provide code but i dont know which one. i'll update it later if its necessary. now i just attach the error.</p>
  
  <blockquote>
    <p>System.ArgumentNullException: Value cannot be null.
    Parameter name: property
       at Microsoft.EntityFrameworkCore.Utilities.Check.NotNull[T](T value, String parameterName)
       at Microsoft.EntityFrameworkCore.Storage.RelationalTypeMapper.FindMapping(IProperty property)
       at Microsoft.EntityFrameworkCore.Migrations.MySqlMigrationsSqlGenerationHelper.ColumnDefinition(String schema, Strin
    g table, String name, Type clrType, String type, Nullable<code>1 unicode, Nullable</code>1 maxLength, Boolean rowVersion, Boolean
    nullable, Object defaultValue, String defaultValueSql, String computedColumnSql, IAnnotatable annotatable, IModel model
    , MigrationCommandListBuilder builder)
       at Microsoft.EntityFrameworkCore.Migrations.MigrationsSqlGenerator.ColumnDefinition(AddColumnOperation operation, IM
    odel model, MigrationCommandListBuilder builder)
       at Microsoft.EntityFrameworkCore.Migrations.MigrationsSqlGenerator.Generate(CreateTableOperation operation, IModel m
    odel, MigrationCommandListBuilder builder, Boolean terminate)
       at Microsoft.EntityFrameworkCore.Migrations.MigrationsSqlGenerator.Generate(CreateTableOperation operation, IModel m
    odel, MigrationCommandListBuilder builder)
       at Microsoft.EntityFrameworkCore.Migrations.MigrationsSqlGenerator.Generate(MigrationOperation operation, IModel mod
    el, MigrationCommandListBuilder builder)
       at Microsoft.EntityFrameworkCore.Migrations.MigrationsSqlGenerator.Generate(IReadOnlyList`1 operations, IModel model
    )
       at Microsoft.EntityFrameworkCore.Migrations.Internal.Migrator.GenerateUpSql(Migration migration)
       at Microsoft.EntityFrameworkCore.Migrations.Internal.Migrator.Migrate(String targetMigration)
       at Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.UpdateDatabase(String targetMigration, String
    contextType)
       at Microsoft.EntityFrameworkCore.Design.OperationExecutor.UpdateDatabase.&lt;>c__DisplayClass0_1.&lt;.ctor>b__0()
       at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)
    Value cannot be null.
    Parameter name: property
    reformat stacktrace</p>
  </blockquote>
  
  <p>any response would be great. thank you very much.</p>