Claims-based authentication is an essential component to enable the advanced functionality of SharePoint 2013.

To move classic-mode web applications from SharePoint 2010 Products to SharePoint 2013, you can convert them to claims-based web applications within SharePoint 2010 Products, and then migrate them to SharePoint 2013.

The procedures in this post will address the issue I had faced after upgrading to SharePoint 2013 from 2010.

Due to classic mode authentication being officially depreciated by Microsoft, the database needed to be updated to claims based authentication.

During my testing; I noticed many (if not all) users accounts had issued logging into sites which worked prior to the upgrade.  I was removing and re adding them to work around this issue ; which was very tedious.

Using the Convert-SPWebApplication PowerShell command simplified this task.

Here are the steps I took

Launched SharePoint 2013 Management Shell as Administrator

Enter the following commands

Convert-SPWebApplication -Identity <URL> -To Claims -RetainPermissions

Please note the <URL> is the http://address to your SharePoint 2013 site application. Example:

For more info check out: