gistfile1.txt

Checking for a new Ubuntu release
Your Ubuntu release is not supported anymore.
For upgrade information, please visit:
http://www.ubuntu.com/releaseendoflife

Get:1 Upgrade tool signature [819 B]                                                                                                                                                  
Get:2 Upgrade tool [1,247 kB]                                                                                                                                                          
Fetched 1,247 kB in 0s (0 B/s)                                                                                                                                                        
authenticate 'artful.tar.gz' against 'artful.tar.gz.gpg' 
extracting 'artful.tar.gz'

Reading cache

Checking package manager

Cannot upgrade 

An upgrade from 'yakkety' to 'artful' is not supported with this 
tool.