I seem to be having a problem when I use
sudo apt-get update &
sudo apt-get upgrade.
I get this:- photos enclosed.]2
You have misconfigured your proxy.
Go to Configuration -> Network -> Proxy settings. Change the actual value ( Automatic or 192.168.1.2) to "Direct connection to Internet"
Save new settings and restart network from terminal with the command :
sudo service network-manager restart
Try apt-get update again
follow the steps below to fix it :-
Open /etc/apt/sources.list file.
Now check whether xyz is present at this path. If it is not present, then replace xyz with the element which is present in 'dists' such as:- saucy, lucid, trusty etc.Now run
sudo apt-get update
Source : WebCheerz.com