I was just spinning up a little console application, as a utility, and I'm pulling an encrypted connection string from the app.config file. Using 1.1 code that I'm used to, I used....

System.Configuration.ConfigurationSettings.AppSettings["connstr"].ToString();

And the compiler gave me the following error.

Warning 1 'System.Configuration.ConfigurationSettings.AppSettings' is obsolete: 'This method is obsolete, it has been replaced by ConfigurationManager.AppSettings'

So I try and change my Code to the following ...

System.Configuration.ConfigurationManager.AppSettings["connstr"].ToString();

and I get a compiler error, saying the compiler can't find ConfigurationManager.

Well here's the confusion.... The Original System.Configuration.ConfigurationSettings class is found in the System.dll assembly. There is a new assembly with all the new ConfigurationManager classes as System.Configuration.dll. Before using the ConfigurationManager class, you must first set a reference to the new System.Configuration.dll.

-=- Hope this helps someone ....