无法从 14.04 升级到 16.04。我正在尝试sudo do-release-upgrade，但失败并出现以下错误：
Calculating the changes
Could not calculate the upgrade
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
/var/log/dist-upgrade/main.log https://www.dropbox.com/s/3gf1tg8uxmn75jq/main.log?dl=0 /var/log/dist-upgrade/apt.log https://www .dropbox.com/s/79i2mf320pvg3bl/apt.log?dl=0
我不明白为什么包管理器无法解决这个问题以及这个问题的根源是什么包。 …