sudo apt update


Ign:1 http://dl.google.com/linux/chrome/deb stable InRelease
Scaricamento di:2 http://security.ubuntu.com/ubuntu xenial-security InRelease [102 kB]
Trovato:3 http://dl.google.com/linux/chrome/deb stable Release                 
Trovato:4 http://it.archive.ubuntu.com/ubuntu xenial InRelease                 
Trovato:5 http://ppa.launchpad.net/numix/ppa/ubuntu xenial InRelease           
Scaricamento di:6 http://it.archive.ubuntu.com/ubuntu xenial-updates InRelease [102 kB]
Ign:7 http://ppa.launchpad.net/varlesh-l/papirus-pack/ubuntu xenial InRelease  
Err:9 http://ppa.launchpad.net/varlesh-l/papirus-pack/ubuntu xenial Release    
  404  Not Found
Scaricamento di:10 http://it.archive.ubuntu.com/ubuntu xenial-backports InRelease [102 kB]
Trovato:11 https://packagecloud.io/slacktechnologies/slack/debian jessie InRelease
Lettura elenco dei pacchetti... Fatto
E: The repository 'http://ppa.launchpad.net/varlesh-l/papirus-pack/ubuntu xenial Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.