Failed to fetch on `apt-get update` with Ubuntu 16.04 sever(CLI) on raspberry pi 3

Question

I have trouble with the Ubuntu 16.04 on Raspberry Pi 3B sever problem.

When I type $ sudo apt-get update ,
it will shows the error message:

Fail to fetch 

The image are here for the evidence:

err1: http://ports.ubuntu.com/ubuntu-ports xenial InRelease
Temporary failure resolving 'ports.ubuntu.com'

err2: http://ppa.launchpad.net/ubuntu-raspi2/ppa-rpi3/ubuntu  xenial InRelease
Temporary failure resolving 'ppa.launchpad.net'
...

Reading Package lists...Done

W:Failure to fetch http://ports.ubuntu.com/ubuntu-ports/dists/xenial/InRelease Temporary failure resolving 'ports.ubuntu.com'

...

W: Some index files failed to download. They have been ignored, or old one used instead.

How can I fix it??

Thank you for all your help!

Answer 1

This is likely because you don't have network connectivity on the Raspberry Pi. First check if you actually can reach the Internet via:

ping google.com

If this fails then you need to connect the Raspberry Pi to the Internet first.