I got the following error message when trying to update Ubuntu 20.04 with sudo apt update.
Err:27 http://ppa.launchpad.net/me-davidsansome/clementine/ubuntu focal Release
404 Not Found [IP: 2001:67c:1560:8008::19 80]
Err:28 http://ppa.launchpad.net/mefrio-g/plymouthmanager/ubuntu focal Release
404 Not Found [IP: 2001:67c:1560:8008::19 80]
Err:29 http://ppa.launchpad.net/vantuz/cool-retro-term/ubuntu focal Release
404 Not Found [IP: 2001:67c:1560:8008::19 80]
Reading package lists... Done
E: The repository 'http://ppa.launchpad.net/me-davidsansome/clementine/ubuntu focal 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.
E: The repository 'http://ppa.launchpad.net/mefrio-g/plymouthmanager/ubuntu focal 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.
E: The repository 'http://ppa.launchpad.net/vantuz/cool-retro-term/ubuntu focal 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.
