Ошибка обновления с 18.04 по 20.04 -

Я пытался "сделать-релиз-обновить" с 18.04 по 20.04, но обновление не удалось.

Could not calculate the upgrade 

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'. 

Restoring original system state
Aborting

Журналы показывают:

https://pastebin.com/CFXJ908H (apt.log) https://pastebin.com/EYJGFUU2 (main.log)

Есть сведения о том, что может пойти не так?