Cisco Umbrella is modifying the auto-upgrade behavior for Umbrella Virtual Appliances.
Currently upgrade failure for even a single VA blocks VA upgrades at an org-level i.e. if a single VA fails to upgrade for any reason, other VAs in the customer org will not attempt to upgrade.
Given that this behavior has resulted in multiple VAs running older versions and not being able to benefit from the features and patches released regularly, this behavior is being modified.
Upgrade failure for any single VA will now block VA upgrades at an Umbrella site level i.e. if a single VA fails to upgrade, other VAs in the same Umbrella site will not attempt to upgrade. However, VAs in other Umbrella sites in the same customer org will continue to upgrade.
Note that Cisco recommends deploying at least 2 VAs per site. If there is only one VA deployed in an Umbrella site, it will not auto-upgrade.