Launching upgradeAPS1ToAPS2.py for a subscription fails with the following error:
Subscription status is Disabling service but it should be 'Ready'. Make sure there are no pending POA tasks for the subscription.
The status of Office 365 instance for this subscription is "Disabling service", a transient state that was set as a result of account/subscription suspension in the past and some related APS 1.2 tasks got canceled.
Fix the state of the APS 1.2 instance.
In case no failed or canceled tasks exist and the service in MOP is active, fix the instance state manually by following the steps from this article.