发布MVC4（EF6.0)出错

出错：

The Entity Framework provider type ‘System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089‘ for the ‘System.Data.SqlClient‘ ADO.NET provider could not be loaded. Make sure the provider assembly is available to the running application.

See http://go.microsoft.com/fwlink/?LinkId=260882 for more information..

找了好几个小时

找到这篇文章

http://stackoverflow.com/questions/14033193/entity-framework-provider-type-could-not-be-loaded

我还没看懂，我就试着在EF上下文中添加了

public void FixEfProviderServicesProblem()
{

var instance = System.Data.Entity.SqlServer.SqlProviderServices.Instance;
}

再发布一次，居然可以了，感觉好难过