Starting just a few days ago, Plesk 11 migrating sites from Plesk 8 has begun generating errors changing subscription owners, the same as what's described in this Plesk 10 thread from a year ago:
http://forum.parallels.com/showthread.php?245946-10-4-4-Fatal-Error-Changing-subscription-owners
This was not happening in Plesk 11 as recently as a week ago, just in our newest installs, so I suspect some update has been released that is causing it. The fix is to go in and edit psa.domains to alter the cl_id and vendor_id to match the subscriber you want to own the domain.
http://forum.parallels.com/showthread.php?245946-10-4-4-Fatal-Error-Changing-subscription-owners
Reassigning Selected Subscriptions
ERROR: PleskFatalException
Picker not supported
0: UIPointer.php:611
UIPointer->accessPicker(string 'GET', object of type plesk__client__domain__chowner)
1: UIPointer.php:593
UIPointer->access(string 'GET')
2: plesk.php:45
This was not happening in Plesk 11 as recently as a week ago, just in our newest installs, so I suspect some update has been released that is causing it. The fix is to go in and edit psa.domains to alter the cl_id and vendor_id to match the subscriber you want to own the domain.