According to Microsoft documentation, Migrate from classic-mode to claims-based authentication in SharePoint 2013, the way to upgrade a classic-authenticated users would be to attach a database to a classic authhentication web application and after that convert that web application to be using claims.
I'm in a little different situation where i just cant grab one single database in 2010 and upgrade all the content directly because of several reason. One of the biggest reasons is that our environment in 2010 is based on one single site collection and hundreds of sub sites, so what i'am doing is moving the biggest sub sites to their own site collections and their own database.
So i'm basically moving one site collection at a time to 2013, and upgrades that database. And after that i move the site collection to the main Db.
My question is, do i have to attach every single database to a dummy web application to migrate the users to claims?
I did find this script that does exactly what i need, and i have been testing it out on multiple times with the desired results, converting a database to claims instead of converting a web application.
$wa = Get-SPWebApplication http://my-app-url $acc = "domain\farm-account" $arguments = New-Object Microsoft.SharePoint.Administration.SPWebApplication+SPMigrateUserParameters $contentDb = $wa.ContentDatabase["Content Database Name"] $arguments.AddDatabaseToMigrate($contentDb) $wa.MigrateUsersToClaims($acc, $false, $arguments)