无法从16.04升级到18.04，没有真正的错误？

我收到通知，我的桌面安装有更新，但我无法这样做。 我看不到真正的错误消息。 我运行了sudo apt autoremove ， sudo apt upgrade和sudo apt install ，它提供0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded 。 当我运行do-release-upgrade时，这是我的屏幕：

 Reading cache Checking package manager Reading package lists... Done Building dependency tree Reading state information... Done Hit http://us.archive.ubuntu.com/ubuntu xenial InRelease Hit http://archive.canonical.com xenial InRelease Hit http://security.ubuntu.com/ubuntu xenial-security InRelease Fetched 0 B in 0s (0 B/s) Reading package lists... Done Building dependency tree Reading state information... Done Restoring original system state Aborting Reading package lists... Done Building dependency tree Reading state information... Done === Command detached from window (Mon Aug 20 20:34:56 2018) === 

这是我的main.log：

 2018-08-20 20:34:50,649 INFO Using config files '['./DistUpgrade.cfg.xenial']' 2018-08-20 20:34:50,649 INFO uname information: 'Linux egwene 4.4.0-133-generic #159-Ubuntu SMP Fri Aug 10 07:26:31 UTC 2018 i686' 2018-08-20 20:34:50,862 INFO apt version: '1.2.15ubuntu0.2' 2018-08-20 20:34:50,862 INFO python version: '3.5.2 (default, Nov 23 2017, 16:37:01) [GCC 5.4.0 20160609]' 2018-08-20 20:34:50,864 INFO release-upgrader version '18.04.24' started 2018-08-20 20:34:50,868 INFO locale: 'en_US' 'UTF-8' 2018-08-20 20:34:51,059 DEBUG Using 'DistUpgradeViewText' view 2018-08-20 20:34:51,111 DEBUG enable dpkg --force-overwrite 2018-08-20 20:34:51,150 DEBUG creating statefile: '/var/log/dist-upgrade/apt-clone_system_state.tar.gz' 2018-08-20 20:34:54,329 DEBUG lsb-release: 'xenial' 2018-08-20 20:34:54,330 DEBUG _pythonSymlinkCheck run 2018-08-20 20:34:54,331 DEBUG openCache() 2018-08-20 20:34:54,332 DEBUG No such plugin directory: ./plugins 2018-08-20 20:34:54,332 DEBUG plugins for condition 'PreCacheOpen' are '[]' 2018-08-20 20:34:54,332 DEBUG plugins for condition 'bionicPreCacheOpen' are '[]' 2018-08-20 20:34:54,332 DEBUG plugins for condition 'from_xenialPreCacheOpen' are '[]' 2018-08-20 20:34:54,333 DEBUG quirks: running PreCacheOpen 2018-08-20 20:34:54,333 DEBUG running Quirks.PreCacheOpen 2018-08-20 20:34:54,721 DEBUG /openCache(), new cache size 56038 2018-08-20 20:34:54,721 DEBUG need_server_mode(): run in 'desktop' mode, (because of pkg 'ubuntu-desktop') 2018-08-20 20:34:54,721 DEBUG checkViewDepends() 2018-08-20 20:34:54,721 DEBUG running doUpdate() (showErrors=False) 2018-08-20 20:34:55,529 DEBUG openCache() 2018-08-20 20:34:55,939 DEBUG /openCache(), new cache size 56038 2018-08-20 20:34:55,940 DEBUG doPostInitialUpdate 2018-08-20 20:34:55,940 DEBUG plugins for condition 'PostInitialUpdate' are '[]' 2018-08-20 20:34:55,940 DEBUG plugins for condition 'bionicPostInitialUpdate' are '[]' 2018-08-20 20:34:55,940 DEBUG plugins for condition 'from_xenialPostInitialUpdate' are '[]' 2018-08-20 20:34:55,940 DEBUG quirks: running bionicPostInitialUpdate 2018-08-20 20:34:55,940 DEBUG running Quirks.bionicPostInitialUpdate 2018-08-20 20:34:55,951 DEBUG abort called 2018-08-20 20:34:55,951 DEBUG openCache() 2018-08-20 20:34:55,951 DEBUG failed to SystemUnLock() (E:Not locked) 2018-08-20 20:34:56,356 DEBUG /openCache(), new cache size 56038 

这可能是什么问题？

编辑

使用WinEunuuchs2Unix提供的链接，这是我的PPA链接：

 'http://us.archive.ubuntu.com/ubuntu/ xenial main restricted' 'http://us.archive.ubuntu.com/ubuntu/ xenial universe' 'http://us.archive.ubuntu.com/ubuntu/ xenial multiverse' 'http://security.ubuntu.com/ubuntu xenial-security main restricted' 'http://security.ubuntu.com/ubuntu xenial-security universe' 'http://security.ubuntu.com/ubuntu xenial-security multiverse' 'http://archive.canonical.com/ xenial partner'