Fixing Instance Failure when connecting to SQL Server

 

I was getting Instance Failure when connecting to my SQL Server Express 2005 Database in my C# ASP.NET application.  Very weird.

<connectionStrings>
    <add name="NorthwindConnString" 
         connectionString="Data Source=.\\SQLEXPRESS;Initial Catalog=Northwind;Integrated Security=True" 
         providerName="System.Data.SqlClient"/>
</connectionStrings>

Trial and error just taught me that the problem was "Data Source=.\\SQLEXPRESS;" - It's the double \\. That's an escape sequence in C#. Everything worked when I switched the connection string to .\SQLEXPRESS.