sudo add-apt-repository ppa:ubuntu-audio-dev/ppa
 This PPA will be used to provide testing versions of packages for supported Ubuntu releases.
 More info: https://launchpad.net/~ubuntu-audio-dev/+archive/ubuntu/ppa
Press [ENTER] to continue or Ctrl-c to cancel adding it.

Hit:1 http://ar.archive.ubuntu.com/ubuntu bionic InRelease
Ign:2 http://dl.google.com/linux/chrome/deb stable InRelease
Get:3 http://ar.archive.ubuntu.com/ubuntu bionic-updates InRelease [88,7 kB]
Hit:4 http://dl.google.com/linux/chrome/deb stable Release
Hit:5 https://download.docker.com/linux/ubuntu bionic InRelease
Hit:6 https://deb.nodesource.com/node_12.x bionic InRelease
Get:7 http://ar.archive.ubuntu.com/ubuntu bionic-backports InRelease [74,6 kB]
Get:9 https://typora.io/linux ./ InRelease [793 B]
Ign:10 http://ppa.launchpad.net/ubuntu-audio-dev/ppa/ubuntu bionic InRelease
Get:11 http://security.ubuntu.com/ubuntu bionic-security InRelease [88,7 kB]
Hit:12 http://packages.microsoft.com/repos/vscode stable InRelease
Err:13 http://ppa.launchpad.net/ubuntu-audio-dev/ppa/ubuntu bionic Release
  404  Not Found [IP: 91.189.95.83 80]
Reading package lists... Done
W: Skipping acquire of configured file 'stable/source/Sources' as repository 'https://download.docker.com/linux/ubuntu bionic InRelease' does not seem to provide it (sources.list entry misspelt?)
E: The repository 'http://ppa.launchpad.net/ubuntu-audio-dev/ppa/ubuntu bionic 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.