Hi,
I have seen recently that the sitecollection became orphan was not allowing to upgrade the features.
then identified the site collection and ran below command to delete it
Stsadm –o deletesite –force –siteid A0FE2A62-152A-4D0E-93EA-4C61E264ED65 –databasename WSS_Content_Database_3 –databaseserver ContentDatabase1
It will give you
Operation completed successfully.
YOGESHA H P(MCTS)