Upgrading from 14.04 to 16.04

[mau42]

As the title says, i am upgrading from 14.04 to 16.04. I did this by clicking "Yes, upgrade now" in the pop-up notification of a new release. Problem is the upgrade has been running for quite a few hours now, and it doesn't finish.
Anyone knows why this could be happening?
Is there a way i can safely abort the upgrade?
Here's a screenshot, the process bar is moving from side to side, so it seems it's still doing stuff.

Thanks in advance.

[RobGoss]

Were you successful with this upgrade? I recommend when upgrading from lets say 14.04 to 16.04, the best approach is to do a clean installation make sure you backup any and all important documents and data. I see to many people having trouble upgrading within the system I'm not really sure why this happens

[mau42]

Turns out the little terminal was waiting for an answer. The upgrade continued for a bit, but now is stuck at "Preparing python3-pkg-resources (amd64)" (about 2 hours now), all i can see in the terminal is [More]_, and is stuck at the mini-size of the first screenshot. Any help is still appreciated.

[RobGoss]

Do you have your system backed up?

[mau42]

Hey, thanks for replying. No, I'm still struggling, check the reply i just posted. Here's a screenshot of current state. And no, i don't have a backup

[RobGoss]

If the upgrade has not completed by now there is clearly something wrong at this point, you might have to abort it and see what the out come is. If you're not able to boot in to the desktop you might have to do a clean installation

[russkyca]

What is the best way to do a backup? I've never done one before. I usually just store documents and files I want onto a HDD. I was trying to use clonezilla but I am not sure how it works - the image created will be the size of the data you want to store or back up? Sorry to OP for interrupting.

I am also trying to do an upgrade but 15.10 to 16.04. Is my 1 TB HDD the only choice to use? I have 8gb thumb drives but the image will be too large?