EF 7 Beta 8 - > EF7 RC1 - 不再可以創建遷移

在嘗試將我的現有項目從beta 8更改為RC1後，我在運行dnx ef migrations add Init後得到以下內容

System.TypeLoadException: Could not load type 'Microsoft.Data.Entity.Scaffolding.SqliteDesignTimeServices, EntityFramework.Sqlite.Design'.
  at Microsoft.Data.Entity.Design.Internal.DesignTimeServicesBuilder.ConfigureProviderServices (System.String provider, IServiceCollection services, Boolean throwOnError) [0x00000] in <filename unknown>:0 
  at Microsoft.Data.Entity.Design.Internal.DesignTimeServicesBuilder.Build (Microsoft.Data.Entity.DbContext context) [0x00000] in <filename unknown>:0 
  at Microsoft.Data.Entity.Design.MigrationsOperations.AddMigration (System.String name, System.String outputDir, System.String contextType) [0x00000] in <filename unknown>:0 
  at Microsoft.Data.Entity.Commands.Program+Executor+<>c__DisplayClass6_0.<AddMigration>b__0 () [0x00000] in <filename unknown>:0 
  at Microsoft.Data.Entity.Commands.Program+Executor.Execute (System.Action action) [0x00000] in <filename unknown>:0 
Could not load type 'Microsoft.Data.Entity.Scaffolding.SqliteDesignTimeServices, EntityFramework.Sqlite.Design'.

我的project.json文件包含以下其他文件

System.TypeLoadException: Could not load type 'Microsoft.Data.Entity.Scaffolding.SqliteDesignTimeServices, EntityFramework.Sqlite.Design'.
  at Microsoft.Data.Entity.Design.Internal.DesignTimeServicesBuilder.ConfigureProviderServices (System.String provider, IServiceCollection services, Boolean throwOnError) [0x00000] in <filename unknown>:0 
  at Microsoft.Data.Entity.Design.Internal.DesignTimeServicesBuilder.Build (Microsoft.Data.Entity.DbContext context) [0x00000] in <filename unknown>:0 
  at Microsoft.Data.Entity.Design.MigrationsOperations.AddMigration (System.String name, System.String outputDir, System.String contextType) [0x00000] in <filename unknown>:0 
  at Microsoft.Data.Entity.Commands.Program+Executor+<>c__DisplayClass6_0.<AddMigration>b__0 () [0x00000] in <filename unknown>:0 
  at Microsoft.Data.Entity.Commands.Program+Executor.Execute (System.Action action) [0x00000] in <filename unknown>:0 
Could not load type 'Microsoft.Data.Entity.Scaffolding.SqliteDesignTimeServices, EntityFramework.Sqlite.Design'.

我該怎麼做才能解決此錯誤？