Background
From sk104848 we learn:
The default virtual network adapter emulated in a Virtual Machine is commonly an AMD PCnet32 device (vlance / "Flexible").
Using "Flexible" NIC driver with Gaia OS is not recommended, as it has been shown to carry a significant performance penalty.
Problem
The GAiA machine’s upgrade to R82 fails after network connectivity is lost mid import process, logs report a license issue among other symptoms, and the system eventually rolls back to the previous version e.g. R81.20
Specifically, this was observed with a Security Management Server which loses it’s eth0 interface and IP address during the upgrade process when using the non-recommended NIC type.
Solution
Important: Ensure you have necessary backups & snapshots of the system.
In a maintenance window power-off the VM and replace / switch the NIC type of the Virtual Machine from Flexible to E1000 (not a long term solution refer: sk180572) or preferably vmxnet3 as outlined in sk104848.
Be wary to preserve the previous mac-address for licensing reasons etc.
CCSM R77/R80/ELITE