Trying to upgrade our VIRL server getting the following error:
An unresolvable problem occurred while calculating the upgrade.
This can be caused by:
* Upgrading to a pre-release version of Ubuntu
* Running the current pre-release version of Ubuntu
* Unofficial software packages not provided by Ubuntu
If none of this applies, then please report this bug using the
command 'ubuntu-bug ubuntu-release-upgrader-core' in a terminal.
Restoring original system state
Check this related document for more info- VIRL 1.2.83 (October 2016 Release) - 31438 - The Cisco Learning Network