c# – Add-Migration Value不能为null.参数名称：语言

我试图创建一个新的迁移,但我得到一个System.ArgumentNullException
他说：

System.ArgumentNullException: Value cannot be null.
Parameter name: language
    at Microsoft.EntityFrameworkCore.Utilities.Check.NotNull[T](T value,String parameterName)
    at Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations..ctor
    (IOperationReporter reporter,Assembly assembly,Assembly 
    startupAssembly,String projectDir,String rootNamespace,String 
    language)
    at Microsoft.EntityFrameworkCore.Design.OperationExecutor.<>c__displayClass4_0.<.ct
    or>b__4()
    at Microsoft.EntityFrameworkCore.Internal.LazyRef`1.get_Value()
    at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigrationImpl(String name,String outputDir,String contextType)
    at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.<>c__displayClass3_0`1.<Execute>b__0()
    at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)
Value cannot be null.
Parameter name: language

解决方法

它与EF Core而不是EF6有关,看起来2.1.0.preview1-final版本中存在一个错误.

• Check the version you are running with dotnet ef –version
• Downgrade to the Microsoft.EntityFrameworkCore.Design 2.0.1 version.