提供程序未返回 ProviderManifestToken 字符串

我这是在学习MVC3.0时出现的错误，其实呢这个问题主要是因为web.config配置文件访问数据库的时候连接出错造成的

  <connectionStrings>
    <add name="ApplicationServices"
         connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|aspnetdb.mdf;User Instance=true"
         providerName="System.Data.SqlClient" />
    <add name="MovieDBContext" connectionString=" Data Source=.\SQLEXPRESS; Initial Catalog=Movies;Persist Security Info=True; User ID=sa;Password=123456 " providerName="System.Data.SqlClient" />
  </connectionStrings>

改为

  <connectionStrings>
    <add name="ApplicationServices"
         connectionString="data source=.;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|aspnetdb.mdf;User Instance=true"
         providerName="System.Data.SqlClient" />
    <add name="MovieDBContext" connectionString=" Data Source=.; Initial Catalog=Movies;Persist Security Info=True; User ID=sa;Password=123456 " providerName="System.Data.SqlClient" />
  </connectionStrings>

原因：因为你登陆数据库的时候用的服务器名称是"."，所以不能用".\SQLEXPRESS"