I’ve recently been involved in upgrading a number of Parallels Plesk installations from version 9.5.4 (or sometimes earlier) to 10.4.4+. Because of the model changes between version 9 and version 10 during the upgrade a bootstrap script runs which tries to convert the majority of clients and domains into customers and ‘custom subscriptions’. Unfortunately for a lot of setups this isn’t entirely straight forward and after the installation completes under the ‘Tools’ menu there’s an option named ‘Complete Switching to the Panel 10 Business Model’ which must be run to transition any remaining customers and subscriptions that do not ‘fit’.
For the majority you can use the recommended actions in completing the transitions and most customers and subscriptions will transition fine. If not, maybe the below scenarios will help:
1. If you receive the error ‘Error: Some of the selected customers and subscriptions were not transitioned.’ then to fix this you will need to use the selective transition model under ‘selective transition of customers’ OR ‘selective transition of Subscriptions’ and try applying an alternative transition scheme – hopefully this will work. You may find that by traversing into an individual customer or subscription and using the ‘Apply Transition Scheme’ may give more useful errors, i.e. ‘Domain limits exceeding Subscription’.
2. If you find that you’re left with a lot of customers and subscriptions that will not transition and there’s no error the only way to work around this is to move the subscriptions to one customer then move them back by using the ‘change subscriber’.
Hope this helps!