SharePoint 2010 Claims to Classic and Classic to Claims

Your running SharePoint 2010 and you want to switch your Authentication Provider between either Claims Based Authentication(CBA) or Classic Authentication, before embarking on changing the authentication provider I would first recommend reading the following technical articles:

http://technet.microsoft.com/en-us/library/gg251985.aspx
http://technet.microsoft.com/en-us/library/cc262350.aspx#section2

CLASSIC to CLAIMS


$webApp = Get-SPWebApplication "http://url"
$webApp.UseClaimsAuthentication = $True;
$webApp.Update()

then run ‘iisreset’

However if you are unable to login suggest re-running and reviewing the second MS article above, espesically the MigrateUsers powershell cmdlet;

$w = Get-SPWebApplication "http://url"
$w.MigrateUsers(1)

CLAIMS to CLASSIC

If you want to switch the web application from Claims to Classic run the following powershell command:


$webApp = Get-SPWebApplication "http://url"
$webApp.UseClaimsAuthentication = $False;
$webApp.Update()

then run ‘iisreset’

You may need to make sure in IIS that the web application security settings is still Windows Authentication and also confirm that the web application Authentication Provider in Central Administration has also been updated.