How do I solve "Unable to fetch some archives, maybe run apt-get update or try with --fix-missing" error?

Try using

sudo apt-get update

then retry.

If sudo apt-get update is also not working then follow the steps below:-

1. Open /etc/apt/sources.list file.
2. Check the word after http://security.ubuntu.com/ubuntu/ in the sources.list file, let the word be xyz
3. Go to the address http://security.ubuntu.com/ubuntu/ and then click on dists. 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.
4. Now run sudo apt-get update command.

There is a command to point source urls in olds releases .

a goog explanation in this github gist :

https://gist.github.com/dergachev/f5da514802fcbbb441a1