删除bin文件夹帮我解决了这个问题

删除bin文件夹帮我解决了这个问题

我得到了同样的错误，而使用实体框架6与SQL Server紧凑4.0。关于EF6实体框架提供者的MSDN的文章很有帮助。在包管理器控制台以nuget包的形式运行相应的提供程序命令可能会解决这个问题，因为nuget包也会自动向配置文件添加注册。我运行PM>安装包实体框架。SqlServerCompact来解决问题。

我抛出了相同的异常。我包括

using System.Data; 
using System.Data.Entity;

一切都恢复正常了。

In my case, everything was working properly then suddenly stopped worked because I think Resharper altered some changes which caused the problem. My project was divided into the data layer, service and presentation layer. I had Entity framework installed and referenced in my data layer but still the error didn't go away. Uninstalling and reinstalling didn't work either. Finally, I solved it by making the data layer the Startup project, making migration, updating the database and changing the Startup project back to my presentation layer.

当错误发生在测试项目时，最漂亮的解决方案是用以下方式装饰测试类:

[DeploymentItem("EntityFramework.SqlServer.dll")]