Problem: Ubuntu Update Manager pops up regularly to remind you of the updates available. Last time it popped up and I installed all the updates, then I noticed this strange message in the Update Manager:
Software updates may be available for your computer.
The Package information was last updated X days ago.
Press the ‘check’ button below to check for new software updates.
This was interesting as clicking on the Check button did nothing but the same message was displayed again. Couple of days later I saw some updates available but after installing the updates I saw the same message again:
What is causing this error? After researching a bit, I found out that there were “sources” other than Canonical (Ubuntu’s official sources) which I had added over the time to install some great indicator applets from private PPAs on my Ubuntu 12.04. Some of these PPAs were old and was meant for earlier version of Ubuntu or they were simply broken. This was the main reason why it showed that there are some updates available even after the recent update.
Now, the next task is to find out which are these “unoffcial troublesome sources” in the list. To find this out run this command and wait for the command to end:
sudo apt-get update
The last few lines of the output of the last command were following:
W: Failed to fetch http://ppa.launchpad.net/fredp/ppa/ubuntu/dists/precise/main/source/Sources 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/fredp/ppa/ubuntu/dists/precise/main/binary-i386/Packages 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/hel-sheep/pastie/ubuntu/dists/precise/main/source/Sources 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/hel-sheep/pastie/ubuntu/dists/precise/main/binary-i386/Packages 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/lookit/ppa/ubuntu/dists/precise/main/source/Sources 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/lookit/ppa/ubuntu/dists/precise/main/binary-i386/Packages 404 Not Found
E: Some index files failed to download. They have been ignored, or old ones used instead.
As you can see in the output, these were the PPAs (name in bold letters) causing trouble.
Once we have the list of the culprits, it’s time to remove them i.e. delete them from the sources list. This can be done in both GUI (Graphical User Interface) and CLI (Command Line Interface). You can opt for any of these 3 ways to do it:
1. Open the terminal (Ctrl+Alt+T) and use the following command:
sudo ls /etc/apt/sources.list.d
In this directory you can see all the sources listed as “.list” file. Remove those which were causing error:
sudo rm /etc/apt/sources.list.d/The_PPA_Name.list
2. Alternatively, apt can be used to remove the PPA repository in the following way:
sudo add-apt-repository --remove ppa:The_PPA_Name/ppa
3. If you are not comfortable with the command line ways, no worries. We have GUI option as well.
Open the Update Manager (Search for it in Unity Dash) and click on Settings:
In here, go for the Other Software tab and here you can see all the additional software sources listed which are included in the update list. Uncheck the box against the troublesome PPAs/sources:
Now when you go to the Update Manager, it should be neat and clean like this:
If not try running the “sudo apt-get update” command again to ensure that everything is smooth there.