我遇到了与软件更新程序完全相同的问题 - 没有自动更新 软件更新程序 - 无自动更新。
简史：当自动软件更新程序出现问题时（无法安装某些软件包），我在论坛上看到并采取了解决方法：安装 Synaptic 软件包管理器并手动进行更新。我关闭了自动更新。一段时间后，我注意到哪些 Ubuntu 软件更新可以正常工作，因此我打开了自动更新。但没有自动更新启动。
软件和更新截图
APT 的输出：
lubomir@lipa:~$ sudo apt-get update
Hit:1 http://sk.archive.ubuntu.com/ubuntu xenial InRelease
Hit:2 http://sk.archive.ubuntu.com/ubuntu xenial-updates InRelease
Hit:3 http://sk.archive.ubuntu.com/ubuntu xenial-backports InRelease
Hit:4 http://security.ubuntu.com/ubuntu xenial-security InRelease
Ign:6 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial InRelease
Hit:7 http://archive.canonical.com/ubuntu xenial InRelease
Hit:8 http://ppa.launchpad.net/webupd8team/java/ubuntu xenial InRelease
Hit:9 https://repo.skype.com/deb stable InRelease
Ign:10 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial Release
Ign:11 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main amd64 Packages
Hit:5 http://screenshots.getdeb.net xenial-getdeb InRelease
Ign:12 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main i386 Packages
Ign:13 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main all Packages
Ign:14 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main Translation-en_US
Ign:15 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main Translation-en
Ign:16 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main amd64 DEP-11 Metadata
Ign:17 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main DEP-11 64x64 Icons
Ign:11 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main amd64 Packages
Ign:12 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main i386 Packages
Ign:13 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main all Packages
Ign:14 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main Translation-en_US
Ign:15 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main Translation-en
Ign:16 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main amd64 DEP-11 Metadata
Ign:17 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main DEP-11 64x64 Icons
Ign:11 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main amd64 Packages
Ign:12 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main i386 Packages
Ign:13 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main all Packages
Ign:14 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main Translation-en_US
Ign:15 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main Translation-en
Ign:16 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main amd64 DEP-11 Metadata
Ign:17 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main DEP-11 64x64 Icons
Ign:11 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main amd64 Packages
Ign:12 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main i386 Packages
Ign:13 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main all Packages
Ign:14 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main Translation-en_US
Ign:15 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main Translation-en
Ign:16 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main amd64 DEP-11 Metadata
Ign:17 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main DEP-11 64x64 Icons
Ign:11 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main amd64 Packages
Ign:12 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main i386 Packages
Ign:13 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main all Packages
Ign:14 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main Translation-en_US
Ign:15 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main Translation-en
Ign:16 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main amd64 DEP-11 Metadata
Ign:17 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main DEP-11 64x64 Icons
Err:11 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main amd64 Packages
404 Not Found
Ign:12 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main i386 Packages
Ign:13 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main all Packages
Ign:14 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main Translation-en_US
Ign:15 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main Translation-en
Ign:16 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main amd64 DEP-11 Metadata
Ign:17 http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial/main DEP-11 64x64 Icons
Reading package lists... Done
W: The repository 'http://ppa.launchpad.net/freefilesync/ffs/ubuntu xenial Release' does not have a Release file.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: Failed to fetch http://ppa.launchpad.net/freefilesync/ffs/ubuntu/dists/xenial/main/binary-amd64/Packages 404 Not Found
E: Some index files failed to download. They have been ignored, or old ones used instead.
lubomir@lipa:~$ sudo apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
The following packages were automatically installed and are no longer required:
akonadi-backend-mysql akonadi-server kde-config-mailtransport kdepim-runtime
kdepimlibs-data kdepimlibs-kio-plugins kinit kio kpackagelauncherqml
kpackagetool5 kwayland-data kwayland-integration libaio1
libboost-thread1.58.0 libfam0 libgrantlee-templates5
libgrantlee-textdocument5 libkf5akonadiagentbase5 libkf5akonadicalendar5
libkf5akonadicontact5 libkf5akonadicore-bin libkf5akonadicore5
libkf5akonadimime5 libkf5akonadinotes5 libkf5akonadiprivate5
libkf5akonadisearchpim5 libkf5akonadiwidgets5 libkf5alarmcalendar5
libkf5archive5 libkf5attica5 libkf5auth-data libkf5auth5
libkf5bookmarks-data libkf5bookmarks5 libkf5calendarcore5
libkf5calendarsupport5 libkf5calendarutils5 libkf5codecs-data libkf5codecs5
libkf5completion-data libkf5completion5 libkf5config-bin libkf5config-data
libkf5configcore5 libkf5configgui5 libkf5configwidgets-data
libkf5configwidgets5 libkf5contacts-data libkf5contacts5
libkf5coreaddons-data libkf5coreaddons5 libkf5crash5 libkf5dbusaddons-bin
libkf5dbusaddons-data libkf5dbusaddons5 libkf5declarative-data
libkf5declarative5 libkf5emoticons-bin libkf5emoticons-data libkf5emoticons5
libkf5eventviews5 libkf5followupreminder5 libkf5gapi-data
libkf5gapicalendar5 libkf5gapicontacts5 libkf5gapicore5 libkf5gapidrive5
libkf5gapitasks5 libkf5globalaccel-bin libkf5globalaccel-data
libkf5globalaccel5 libkf5globalaccelprivate5 libkf5gpgmepp-pthread5
libkf5gpgmepp5 libkf5gravatar5 libkf5guiaddons5 libkf5holidays-data
libkf5holidays5 libkf5i18n-data libkf5i18n5 libkf5iconthemes-bin
libkf5iconthemes-data libkf5iconthemes5 libkf5identitymanagement5
libkf5idletime5 libkf5imap5 libkf5incidenceeditorsng5 libkf5itemmodels5
libkf5itemviews-data libkf5itemviews5 libkf5jobwidgets-data
libkf5jobwidgets5 libkf5kcmutils-data libkf5kcmutils5
libkf5kdelibs4support-data libkf5kdelibs4support5 libkf5kdelibs4support5-bin
libkf5kdepimdbusinterfaces5 libkf5kdgantt2-5 libkf5kiocore5
libkf5kiofilewidgets5 libkf5kiontlm5 libkf5kiowidgets5 libkf5ldap5
libkf5libkdepim5 libkf5libkleo5 libkf5mailcommon5 libkf5mailimporter5
libkf5mailtransport-data libkf5mailtransport5 libkf5mbox5
libkf5messagecomposer5 libkf5messagecore5 libkf5messageviewer5 libkf5mime5
libkf5newstuff-data libkf5newstuff5 libkf5notifications-data
libkf5notifications5 libkf5notifyconfig-data libkf5notifyconfig5
libkf5package-data libkf5package5 libkf5parts-data libkf5parts-plugins
libkf5parts5 libkf5pimcommon5 libkf5pimtextedit5 libkf5qgpgme5
libkf5quickaddons5 libkf5sendlater5 libkf5service-bin libkf5service-data
libkf5service5 libkf5solid5 libkf5solid5-data libkf5sonnet5-data
libkf5sonnetcore5 libkf5sonnetui5 libkf5templateparser5
libkf5textwidgets-data libkf5textwidgets5 libkf5tnef5 libkf5wallet-bin
libkf5wallet-data libkf5wallet5 libkf5waylandclient5 libkf5webkit5
libkf5widgetsaddons-data libkf5widgetsaddons5 libkf5windowsystem-data
libkf5windowsystem5 libkf5xmlgui-bin libkf5xmlgui-data libkf5xmlgui5
libkolab1 libkolabxml1v5 libkwalletbackend5-5 libllvm3.8 libllvm3.8:i386
libllvm4.0 libllvm4.0:i386 libmircommon5 libphonon4qt5-4 libpolkit-qt5-1-1
libqmi-glib1 libqt5script5 libqt5x11extras5 libqt5xmlpatterns5 libvoikko1
libxerces-c3.1 linux-headers-4.4.0-101 linux-headers-4.4.0-101-generic
linux-headers-4.4.0-103 linux-headers-4.4.0-103-generic
linux-headers-4.4.0-104 linux-headers-4.4.0-104-generic
linux-headers-4.4.0-108 linux-headers-4.4.0-108-generic
linux-headers-4.4.0-109 linux-headers-4.4.0-109-generic
linux-headers-4.4.0-81 linux-headers-4.4.0-81-generic linux-headers-4.4.0-83
linux-headers-4.4.0-83-generic linux-headers-4.4.0-87
linux-headers-4.4.0-87-generic linux-headers-4.4.0-91
linux-headers-4.4.0-91-generic linux-headers-4.4.0-92
linux-headers-4.4.0-92-generic linux-headers-4.4.0-93
linux-headers-4.4.0-93-generic linux-headers-4.4.0-96
linux-headers-4.4.0-96-generic linux-headers-4.4.0-97
linux-headers-4.4.0-97-generic linux-headers-4.4.0-98
linux-headers-4.4.0-98-generic linux-image-4.4.0-101-generic
linux-image-4.4.0-103-generic linux-image-4.4.0-104-generic
linux-image-4.4.0-108-generic linux-image-4.4.0-109-generic
linux-image-4.4.0-81-generic linux-image-4.4.0-83-generic
linux-image-4.4.0-87-generic linux-image-4.4.0-91-generic
linux-image-4.4.0-92-generic linux-image-4.4.0-93-generic
linux-image-4.4.0-96-generic linux-image-4.4.0-97-generic
linux-image-4.4.0-98-generic linux-image-extra-4.4.0-101-generic
linux-image-extra-4.4.0-103-generic linux-image-extra-4.4.0-104-generic
linux-image-extra-4.4.0-108-generic linux-image-extra-4.4.0-109-generic
linux-image-extra-4.4.0-81-generic linux-image-extra-4.4.0-83-generic
linux-image-extra-4.4.0-87-generic linux-image-extra-4.4.0-91-generic
linux-image-extra-4.4.0-92-generic linux-image-extra-4.4.0-93-generic
linux-image-extra-4.4.0-96-generic linux-image-extra-4.4.0-97-generic
linux-image-extra-4.4.0-98-generic linux-signed-image-4.4.0-101-generic
linux-signed-image-4.4.0-103-generic linux-signed-image-4.4.0-104-generic
linux-signed-image-4.4.0-108-generic linux-signed-image-4.4.0-109-generic
linux-signed-image-4.4.0-81-generic linux-signed-image-4.4.0-83-generic
linux-signed-image-4.4.0-87-generic linux-signed-image-4.4.0-91-generic
linux-signed-image-4.4.0-92-generic linux-signed-image-4.4.0-93-generic
linux-signed-image-4.4.0-96-generic linux-signed-image-4.4.0-97-generic
linux-signed-image-4.4.0-98-generic mysql-client-core-5.7
mysql-server-core-5.7 sonnet-plugins
Use 'sudo apt autoremove' to remove them.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
这是我删除一个过时的包并运行后的输出apt autoremove：
lubomir@lipa:~$ sudo apt-get update
Hit:1 http://sk.archive.ubuntu.com/ubuntu xenial InRelease
Hit:2 http://sk.archive.ubuntu.com/ubuntu xenial-updates InRelease
Hit:3 http://sk.archive.ubuntu.com/ubuntu xenial-backports InRelease
Hit:5 http://ppa.launchpad.net/webupd8team/java/ubuntu xenial InRelease
Hit:6 http://archive.canonical.com/ubuntu xenial InRelease
Get:7 http://security.ubuntu.com/ubuntu xenial-security InRelease [102 kB]
Hit:4 http://screenshots.getdeb.net xenial-getdeb InRelease
Hit:8 https://repo.skype.com/deb stable InRelease
Fetched 102 kB in 1s (66,1 kB/s)
Reading package lists... Done
lubomir@lipa:~$ sudo apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.