升级到 ubuntu 20.04 时显示此信息
An unresolvable problem occurred while calculating the upgrade:
This was likely caused by
- Protea 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
one of this applies then please report this bug using the command ubuntu bug ubuntu-release upgrader-core ina terminal. it you way to investigate this you thing dist upgrade will contain details about the upgrade. Specifically, look at matulog and apt.log
请帮忙修复这个问题。