I tested an upgrade from Xenial to Bionic with some ROS packages installed from their archive. With the version of ubuntu-release-upgrader from bionic-proposed I received a more informative error message.
An unresolvable problem occurred while calculating the upgrade.
This was likely caused by:
* Unofficial software packages not provided by Ubuntu
Please use the tool 'ppa-purge' from the ppa-purge
package to remove software from a Launchpad PPA and
try the upgrade again.
If none of this applies, then please report this bug using the
command 'ubuntu-bug ubuntu-release-upgrader-core' in a terminal.If
you want to investigate this yourself the log files in
'/var/log/dist-upgrade' will contain details about the upgrade.
Specifically, look at 'main.log' and 'apt.log'.
I tested an upgrade from Xenial to Bionic with some ROS packages installed from their archive. With the version of ubuntu- release- upgrader from bionic-proposed I received a more informative error message.
An unresolvable problem occurred while calculating the upgrade.
This was likely caused by:
* Unofficial software packages not provided by Ubuntu
Please use the tool 'ppa-purge' from the ppa-purge
package to remove software from a Launchpad PPA and
try the upgrade again.
If none of this applies, then please report this bug using the release- upgrader- core' in a terminal.If dist-upgrade' will contain details about the upgrade.
command 'ubuntu-bug ubuntu-
you want to investigate this yourself the log files in
'/var/log/
Specifically, look at 'main.log' and 'apt.log'.
Restoring original system state
Setting to verification-done.