How to Fix ‘Requires installation of untrusted packages’ error in Ubuntu 10.10 Maverick Meerkat

When I try to update my Ubuntu machine, I get an error message "Requires installation packages unstrusted 'and can not figure out why. I later found out that I have lost several key GPG.  
The error screen below is what you’ll get when you try to update your system via Update  Manager or Ubuntu Software center.

If you get the above message while trying to install an application through Ubuntu Software Center (on Ubuntu 10.10 Maverick Meerkat) try the following to fix it:


To fix it, go to Applications –> Accessories’ –> Terminal. and run the command below:

sudo apt-get update

Then take notes of all the numbers (keys) after ‘NO_PUBKEY’. I have underlined my missing keys in the image above.

To install the missing public keys, run the command below for each missing key. Replace XXXXXX with the key shown

sudo apt-key adv --recv-key --keyserver keyserver.ubuntu.com XXXXXXXXX

After that, type the command below to update your package repository with the missing key:

sudo apt-get update

Next, try updating your system again, and this time it should work.

Please ask if you have a problem. Thanks for reading and please come back soon.
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