Resume interupted upgrade (14.04 to 16.04) and

my computer crashed while I was upgrading from Ubuntu 14.04 to 16.04.

In order to resume the upgrade, I followed the steps in this tutorial, which seems quite useful.

Everything worked fine when i ran the command

dpkg --configure -a

but when I ran the commands

sudo apt-get update && sudo apt-get upgrade

, I get the following error message (I could only take a picture of it as in that computer only the terminal is working)

Basically it is saying that it failed to resolve a few packages (e.g. temporary failure to resolve 'gb.archive.ubuntu.com')

I have then found something here, which I believe is pretty much what I have been experiencing (failure DURING dist upgrage). However, I noticed that ALL the entries from my

sources.list

have the name "xenial" after it, therefore I'm affraid closing all the entries from my source.list is not the best option. A picture of my sources.list file can be found below:

Or do anyone of you believe it can be a temporary DNS issue? Or any other thoughts (I have a feeling it has something to do with my sources.list)?

Thanks and best regards