Below the resources of my VM. The Guest OS is "Other 3.x Linux (64 bits), which is normal because It was a R81.20 before upgrading.
What is weird is that in another VM, I installed directly the R82 without any issue using the same Guest OS (Other 3.x Linux (64 bits))
I used a disk of 110 GB where 20GB were assigned for each partition (System-root and logs).
I am sharing some screenshots of the upgrade:
Before starting I clicked "Check for Updates", then I look at (/var/log/CPda/repository the upgrade tools are there
In $FWDIR/scripts/, after verifying, I launched the database export
Then I verified that migrate804811 is in /home/admin
Second part:
I imported the package Check_Point_R82_T777_Gaia_Install_and_Upgrade.tar and I did a clean install from CPUSE.
Once the install done, I clicked again in "Check for updates" to bring in the upgrade tools
migrate840811 file is still on /home/admin
Finally I imported the database
Connecting with the SmartConsole R82, I found all the rules and the SIC displayed an status of "Communicating"
As you see, it worked really well.