Ubuntu – How to fix broken repository information

synapticupdate-managerupdates

I have the small red cross icon in my indicator applet, and upon hovering it says that An error occurred while checking for updates. Because of this, I can't edit the selected repositories through synaptic, which refuses to open the dialog and instead just tries to update the package list.

Get:1 http://dl.google.com stable Release.gpg [197B]
Hit http://archive.ubuntu.com maverick Release.gpg
Ign http://archive.ubuntu.com/ubuntu/ maverick/main Translation-en
Hit http://extras.ubuntu.com maverick Release.gpg
Ign http://extras.ubuntu.com/ubuntu/ maverick/main Translation-en
Hit http://ppa.launchpad.net maverick Release.gpg
Ign http://ppa.launchpad.net/elementaryart/ppa/ubuntu/ maverick/main Translation-en
Ign http://ppa.launchpad.net/elementaryart/ppa/ubuntu/ maverick/main Translation-en_GB
Ign http://dl.google.com/linux/chrome/deb/ stable/main Translation-en
Hit http://archive.ubuntu.com/ubuntu/ maverick/main Translation-en_GB
Ign http://archive.ubuntu.com/ubuntu/ maverick/multiverse Translation-en
Hit http://archive.ubuntu.com/ubuntu/ maverick/multiverse Translation-en_GB
Ign http://archive.ubuntu.com/ubuntu/ maverick/restricted Translation-en
Hit http://archive.ubuntu.com/ubuntu/ maverick/restricted Translation-en_GB
Ign http://archive.ubuntu.com/ubuntu/ maverick/universe Translation-en
Hit http://archive.ubuntu.com/ubuntu/ maverick/universe Translation-en_GB
Hit http://archive.ubuntu.com maverick-updates Release.gpg
Ign http://archive.ubuntu.com/ubuntu/ maverick-updates/main Translation-en
Ign http://extras.ubuntu.com/ubuntu/ maverick/main Translation-en_GB
Hit http://extras.ubuntu.com maverick Release
Hit http://ppa.launchpad.net maverick Release.gpg
Ign http://ppa.launchpad.net/nikount/orta-desktop/ubuntu/ maverick/main Translation-en
Ign http://ppa.launchpad.net/nikount/orta-desktop/ubuntu/ maverick/main Translation-en_GB
Hit http://ppa.launchpad.net maverick Release.gpg
Ign http://ppa.launchpad.net/stk/dev/ubuntu/ maverick/main Translation-en
Ign http://ppa.launchpad.net/stk/dev/ubuntu/ maverick/main Translation-en_GB
Hit http://ppa.launchpad.net maverick Release.gpg
Ign http://ppa.launchpad.net/tiheum/equinox/ubuntu/ maverick/main Translation-en
Ign http://ppa.launchpad.net/tiheum/equinox/ubuntu/ maverick/main Translation-en_GB
Ign http://archive.ubuntu.com/ubuntu/ maverick-updates/main Translation-en_GB
Ign http://archive.ubuntu.com/ubuntu/ maverick-updates/multiverse Translation-en
Ign http://archive.ubuntu.com/ubuntu/ maverick-updates/multiverse Translation-en_GB
Ign http://archive.ubuntu.com/ubuntu/ maverick-updates/restricted Translation-en
Ign http://archive.ubuntu.com/ubuntu/ maverick-updates/restricted Translation-en_GB
Hit http://ppa.launchpad.net maverick Release
Hit http://ppa.launchpad.net maverick Release
Hit http://ppa.launchpad.net maverick Release
Hit http://extras.ubuntu.com maverick/main Sources
Ign http://archive.ubuntu.com/ubuntu/ maverick-updates/universe Translation-en
Ign http://archive.ubuntu.com/ubuntu/ maverick-updates/universe Translation-en_GB
Hit http://archive.ubuntu.com maverick-security Release.gpg
Ign http://archive.ubuntu.com/ubuntu/ maverick-security/main Translation-en
Ign http://archive.ubuntu.com/ubuntu/ maverick-security/main Translation-en_GB
Hit http://ppa.launchpad.net maverick Release
Hit http://extras.ubuntu.com maverick/main i386 Packages
Ign http://archive.ubuntu.com/ubuntu/ maverick-security/multiverse Translation-en
Ign http://archive.ubuntu.com/ubuntu/ maverick-security/multiverse Translation-en_GB
Ign http://archive.ubuntu.com/ubuntu/ maverick-security/restricted Translation-en
Ign http://archive.ubuntu.com/ubuntu/ maverick-security/restricted Translation-en_GB
Ign http://archive.ubuntu.com/ubuntu/ maverick-security/universe Translation-en
Hit http://ppa.launchpad.net maverick/main Sources
Hit http://ppa.launchpad.net maverick/main i386 Packages
Ign http://dl.google.com/linux/chrome/deb/ stable/main Translation-en_GB
Ign http://archive.ubuntu.com/ubuntu/ maverick-security/universe Translation-en_GB
Hit http://archive.ubuntu.com maverick Release
Hit http://archive.ubuntu.com maverick-updates Release
Hit http://archive.ubuntu.com maverick-security Release
Hit http://ppa.launchpad.net maverick/main Sources
Hit http://ppa.launchpad.net maverick/main i386 Packages
Hit http://ppa.launchpad.net maverick/main Sources
Hit http://ppa.launchpad.net maverick/main i386 Packages
Get:2 http://dl.google.com stable Release.gpg [197B]
Hit http://archive.ubuntu.com maverick/main Sources
Hit http://ppa.launchpad.net maverick/main Sources
Hit http://ppa.launchpad.net maverick/main i386 Packages
Hit http://archive.ubuntu.com maverick/restricted Sources
Hit http://archive.ubuntu.com maverick/universe Sources
Hit http://archive.ubuntu.com maverick/multiverse Sources
Hit http://archive.ubuntu.com maverick/main i386 Packages
Hit http://archive.ubuntu.com maverick/restricted i386 Packages
Hit http://archive.ubuntu.com maverick/universe i386 Packages
Hit http://archive.ubuntu.com maverick/multiverse i386 Packages
Hit http://archive.ubuntu.com maverick-updates/main Sources
Ign http://dl.google.com/linux/talkplugin/deb/ stable/main Translation-en
Hit http://archive.ubuntu.com maverick-updates/restricted Sources
Hit http://archive.ubuntu.com maverick-updates/universe Sources
Hit http://archive.ubuntu.com maverick-updates/multiverse Sources
Hit http://archive.ubuntu.com maverick-updates/main i386 Packages
Hit http://archive.ubuntu.com maverick-updates/restricted i386 Packages
Hit http://archive.ubuntu.com maverick-updates/universe i386 Packages
Hit http://archive.ubuntu.com maverick-updates/multiverse i386 Packages
Ign http://dl.google.com/linux/talkplugin/deb/ stable/main Translation-en_GB
Get:3 http://dl.google.com stable Release [1,347B]
Hit http://archive.ubuntu.com maverick-security/main Sources
Hit http://archive.ubuntu.com maverick-security/restricted Sources
Hit http://archive.ubuntu.com maverick-security/universe Sources
Hit http://archive.ubuntu.com maverick-security/multiverse Sources
Hit http://archive.ubuntu.com maverick-security/main i386 Packages
Hit http://archive.ubuntu.com maverick-security/restricted i386 Packages
Hit http://archive.ubuntu.com maverick-security/universe i386 Packages
Get:4 http://dl.google.com stable Release [1,347B]
Hit http://archive.ubuntu.com maverick-security/multiverse i386 Packages
Get:5 http://dl.google.com stable/main i386 Packages [1,076B]
Get:6 http://dl.google.com stable/main i386 Packages [735B]
Fetched 4,899B in 4s (1,060B/s)
Reading package lists...

Best Answer

The first step is to cut out the "middle-man" tools and work with commands that are invoked on your behalf:

 sudo apt-get check && sudo apt-get update 
 # you may need to repeat the update if it complains
 sudo apt-get upgrade

Any errors generated by these commands would be most informative when appended to your original question. If the check fails, do as it instructs or stop and post your result.