title: The underlying provider failed on open
body: <p>I know this question has been asked a few times already, but I tried all the solutions I found on stackoverflow and everywhere else and nothing worked, so I'm asking again I'm sorry </p>
  
  <p>I used to connect to a remote database on a server, but to test some things I had to backup this database and restore it locally. The thing is, when I try to replace the server name by ".\SQLEXPRESS" in the connection strings, everytime I try to use the database (juste display datas as exemple), I got the error you can see in the title. </p>
  
  <p>I already tried to Allow remote connections in my local DTC, I tried to open the connection, tried the sp_users command, nothing worked </p>
  
  <p>Here is my connection string : </p>
  
  <pre><code>    &lt;add name="HDPreDiagEntities" connectionString="metadata=res://*/HDPreDiag.csdl|res://*/HDPreDiag.ssdl|res://*/HDPreDiag.msl;provider=System.Data.SqlClient;provider connection string=&amp;quot;data source=.\SQLEXPRESS;initial catalog=HDPreDiag;persist security info=True;user id=id;password=password;MultipleActiveResultSets=True;App=EntityFramework&amp;quot;" providerName="System.Data.EntityClient" /&gt;
  </code></pre>
  
  <p>Thanks guys for your time and help </p>