几周以来，我一直尝试将 14.04 升级到 16.04，但一直没有成功。正如许多其他人（例如，这里)，我收到一条错误消息，提示 Ubuntu“无法计算升级”。我尝试检查/var/log/dist-upgrade/apt.log以找出导致问题的软件包，并获得了大约800个破损包裹：
Broken dpkg:amd64 Breaks on libapache2-mod-php5 [ amd64 ] < 5.5.9+dfsg-1ubuntu4.19 > ( httpd ) (< 5.6.4+dfsg-3~)
Broken perl-base:amd64 Breaks on perl-modules [ amd64 ] < 5.18.2-2ubuntu1.1 > ( perl ) (< 5.22.1~)
Broken findutils:amd64 Breaks on libpython3.4-minimal [ amd64 ] < 3.4.3-1ubuntu1~14.04.4 > ( python ) (< 3.4.4-2)
Broken libgnutls30:amd64 Conflicts on libnettle4 [ amd64 ] < 2.7.1-1ubuntu0.1 > ( libs )
Broken libgnutls30:amd64 Conflicts on libnettle4 [ i386 ] < 2.7.1-1ubuntu0.1 > ( libs )
Broken systemd:amd64 Conflicts on systemd-services [ amd64 ] < 204-5ubuntu20.19 > ( admin )
Broken systemd:amd64 Conflicts on systemd-services [ i386 ] < none > ( none )
Broken texlive-binaries:amd64 Breaks on luatex [ amd64 ] < 0.76.0-3ubuntu1 > ( tex ) (< 2014)
Broken libopencv-core2.4v5:amd64 Conflicts on libopencv-core2.4 [ amd64 ] < 2.4.8+dfsg1-2ubuntu1 > ( libs )
Broken gnome-control-center:amd64 Breaks on libgnome-control-center1 [ amd64 ] < 1:3.6.3-0ubuntu56.1 > ( libs )
Broken xserver-xorg-core:amd64 Conflicts on xserver-xorg-video-glamoregl [ amd64 ] < 0.6.0+git1603170630.347ef4~gd~t > ( x11 )
Broken xserver-xorg-core:amd64 Conflicts on xserver-xorg-video-modesetting [ amd64 ] < 0.8.1-1build1 > ( x11 )
Broken unity-control-center-faces:amd64 Conflicts on gnome-control-center-shared-data [ amd64 ] < 1:3.6.3-0ubuntu56.1 > ( gnome )
Broken libaccount-plugin-generic-oauth:amd64 Conflicts on account-plugin-windows-live [ amd64 ] < 0.11+14.04.20140409.1-0ubuntu2 > ( gnome )
Broken ghc-doc:amd64 Breaks on libghc-transformers-doc [ amd64 ] < 0.3.0.0-5 > ( doc ) (< 0.3.0.0-6)
Broken libasprintf0v5:amd64 Breaks on libasprintf0c2 [ amd64 ] < 0.18.3.1-1ubuntu3 > ( libs )
Broken libopencv-imgproc2.4v5:amd64 Conflicts on libopencv-imgproc2.4 [ amd64 ] < 2.4.8+dfsg1-2ubuntu1 > ( libs )
这个清单可以列得很长，但可能已经说明了发生了什么。无论如何，我提交了一份错误报告在 Ubuntu 跟踪器上，被告知问题可能是我安装了与新版本不兼容的 PPA 软件包。他们建议我使用 删除这些软件包ppa-purge，特别是从oibafPPA 中删除：
sudo ppa-purge oibaf
然而，我收到一个错误：
Updating packages lists
PPA to be removed: oibaf ppa
Warning: Could not find package list for PPA: oibaf ppa
关于如何解决这个问题有什么线索吗？