launchpad Not Found

[behnambm]

$ sudo add-apt-repository ppa:tualatrix/ppa

The official Ubuntu Tweak stable repository
More info: https://launchpad.net/~tualatrix/+archive/ubuntu/ppa
Press [ENTER] to continue or Ctrl-c to cancel adding it.

Ign:1 http://ppa.launchpad.net/tualatrix/ppa/ubuntu bionic InRelease
Hit:2 http://security.ubuntu.com/ubuntu bionic-security InRelease
Hit:3 http://us.archive.ubuntu.com/ubuntu bionic InRelease
** Err:4 http://ppa.launchpad.net/tualatrix/ppa/ubuntu bionic Release
404 Not Found [IP: 91.189.95.83 80]
**
Hit:5 http://us.archive.ubuntu.com/ubuntu bionic-updates InRelease

Hit:6 http://us.archive.ubuntu.com/ubuntu bionic-backports InRelease
Reading package lists... Done
E: The repository 'http://ppa.launchpad.net/tualatrix/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.