How to convert CMA (Classic Mode Authentication) to CBA (Claim Based Authentication)

You can convert a web application that has been configured to use CMA to use CBA using PowerShell only. Once you convert the web application to use CBA, you cannot revert to CMA. Using following PowerShell commands you can convert CMA to CBA

$ConvertApp = get-spwebapplication “http://<your web application name”

$ConvertApp.useclaimsauthentication = “True”

$ConvertApp.Update()