相关疑难解决方法(0)

我首先使用EF6代码来创建我的数据库.昨晚一切都运行良好,现在当我运行update-database命令时,我得到以下异常:

PM> update-database
Specify the '-Verbose' flag to view the SQL statements being applied to the target database.
System.ArgumentNullException: Value cannot be null.
Parameter name: extent
   at System.Data.Entity.Utilities.Check.NotNull[T](T value, String parameterName)
   at System.Data.Entity.Core.Mapping.StorageEntitySetMapping..ctor(EntitySet extent, StorageEntityContainerMapping entityContainerMapping)
   at System.Data.Entity.ModelConfiguration.Edm.DbDatabaseMappingExtensions.AddEntitySetMapping(DbDatabaseMapping databaseMapping, EntitySet entitySet)
   at System.Data.Entity.ModelConfiguration.Edm.Services.TableMappingGenerator.Generate(EntityType entityType, DbDatabaseMapping databaseMapping)
   at System.Data.Entity.ModelConfiguration.Edm.Services.DatabaseMappingGenerator.GenerateEntityTypes(DbDatabaseMapping databaseMapping)
   at System.Data.Entity.ModelConfiguration.Edm.Services.DatabaseMappingGenerator.Generate(EdmModel conceptualModel)
   at System.Data.Entity.DbModelBuilder.Build(DbProviderManifest providerManifest, DbProviderInfo providerInfo)
   at System.Data.Entity.DbModelBuilder.Build(DbConnection providerConnection)
   at System.Data.Entity.Internal.LazyInternalContext.CreateModel(LazyInternalContext internalContext)
   at System.Data.Entity.Internal.RetryLazy`2.GetValue(TInput input)
   at System.Data.Entity.Internal.LazyInternalContext.InitializeContext()
   at System.Data.Entity.Internal.LazyInternalContext.get_CodeFirstModel()
   at System.Data.Entity.Infrastructure.EdmxWriter.WriteEdmx(DbContext context, XmlWriter writer)
   at System.Data.Entity.Utilities.DbContextExtensions.<>c__DisplayClass1.<GetModel>b__0(XmlWriter w)
   at System.Data.Entity.Utilities.DbContextExtensions.GetModel(Action`1 …

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