Error The network path was not found - ASP.NET Website C# - Web.config

 There may be error in web.config connection string

Correct:-

<add key="PermisnetConn" value="Data Source=.\SQLEXPRESS;Initial Catalog=permisnet_new;User Id=sa;Password=Arms#2001"/>

Wrong:-

<add key="PermisnetConn" value="Data Source=SQLEXPRESS;Initial Catalog=permisnet_new;User Id=sa;Password=Arms#2001"/>