Error 4 The name 'ConfigurationManager' does not exist in the current context

You may get "Error    4 The name 'ConfigurationManager' does not exist in the current context" error when you copy the code from old version like 1.1. or 2.0. Microsoft would have given you enough warning by default when you use ConfigurationSettings in your .NET 2.0 or 3.5. From 4.0 onward it will throw error as "Error    4 The name 'ConfigurationManager' does not exist in the current context".

Solution is not that complicated, it is simple and can be resolved in two steps.

First, if you haven't added the reference to the System.Configuration then you must add the reference first.

So from your solution explorer right click on the Reference and open '.NET' tab and then locate the 'System.Configuration' option almost at the bottom.

Once you added the reference or you already have the reference then add the namespace to use ConfigurationManager like below,

using System.Configuration;

or you can use the code directly like below,

String strConnString = System.Configuration.ConfigurationManager.ConnectionStrings["myConnectionString"].ConnectionString;