Converting a SharePoint 2013 Classic Mode web to Claims Based

The process of converting a classic mode application to claims based is fairly straightforward but it is also a one-way street. You should back up the web application before you attempt this procedure. You can accomplish this task by following these steps.

1. Open up the “SharePoint 2013 Management Shell” on one of the application servers using “run as administrator” (make sure you are using the farm account due to the need to create databases and web sites).
   
   
2. Type in the following PowerShell command.
   
   Convert-SPWebApplication -Identity “http:// <servername>:port” -To Claims –RetainPermissions –Force
   
   
3. Wait until the command is completely finished before testing. Validate with additional users to determine if the permissions are still valid.