Why am I unable to update from Software Updater?

Question

I am unable to update through software updater. After clicking install now, it shows "requires installation from untrusted package".

Then there is two options: Settings and OK. I click OK but the software updater window closes and stops.

Answer 1

might be useful to look at your sources file you can get it like this:

cat /etc/apt/sources.list

but you might try this:

sudo apt-get clean
cd /var/lib/apt
sudo mv lists lists.old
sudo mkdir -p lists/partial
sudo apt-get clean 
sudo apt-get update

source