[Bug 1988591] [NEW] apt update fails with ` 404 Not Found [IP: 185.125.190.52 80]`

[Dayashankar Sunda]

Public bug reported:

sudo apt update
Hit:1 http://us.archive.ubuntu.com/ubuntu xenial InRelease
Hit:2 http://us.archive.ubuntu.com/ubuntu xenial-updates InRelease                       
Hit:3 http://us.archive.ubuntu.com/ubuntu xenial-backports InRelease                     
Hit:4 http://security.ubuntu.com/ubuntu xenial-security InRelease                                                                   
Ign:5 http://ppa.launchpad.net/takluyver/matplotlib-daily/ubuntu xenial InRelease                                                   
Hit:6 http://ppa.launchpad.net/yubico/stable/ubuntu xenial InRelease           
Err:7 http://ppa.launchpad.net/takluyver/matplotlib-daily/ubuntu xenial Release
  404  Not Found [IP: 185.125.190.52 80]
Reading package lists... Done
E: The repository 'http://ppa.launchpad.net/takluyver/matplotlib-daily/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.

** Affects: apt (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1988591

Title:
  apt update fails with ` 404 Not Found [IP: 185.125.190.52 80]`

Status in apt package in Ubuntu:
  New

Bug description:
  sudo apt update
  Hit:1 http://us.archive.ubuntu.com/ubuntu xenial InRelease
  Hit:2 http://us.archive.ubuntu.com/ubuntu xenial-updates InRelease                       
  Hit:3 http://us.archive.ubuntu.com/ubuntu xenial-backports InRelease                     
  Hit:4 http://security.ubuntu.com/ubuntu xenial-security InRelease                                                                   
  Ign:5 http://ppa.launchpad.net/takluyver/matplotlib-daily/ubuntu xenial InRelease                                                   
  Hit:6 http://ppa.launchpad.net/yubico/stable/ubuntu xenial InRelease           
  Err:7 http://ppa.launchpad.net/takluyver/matplotlib-daily/ubuntu xenial Release
    404  Not Found [IP: 185.125.190.52 80]
  Reading package lists... Done
  E: The repository 'http://ppa.launchpad.net/takluyver/matplotlib-daily/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.

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