this command is not run on my pc:- sudo add-apt-repository ppa:morphis/anbox-support
duggal@duggal-X556UQK:~$ sudo add-apt-repository ppa:morphis/anbox-support
[sudo] password for duggal:
More info: https://launchpad.net/~morphis/+archive/ubuntu/anbox-support
Press [ENTER] to continue or Ctrl-c to cancel adding it.
Hit:1 http://dl.google.com/linux/chrome/deb stable InRelease
Ign:2 http://ppa.launchpad.net/morphis/anbox-support/ubuntu focal InRelease
Hit:3 http://in.archive.ubuntu.com/ubuntu focal InRelease
Hit:4 http://in.archive.ubuntu.com/ubuntu focal-updates InRelease
Hit:5 http://packages.microsoft.com/repos/vscode stable InRelease
Hit:6 http://in.archive.ubuntu.com/ubuntu focal-backports InRelease
Err:7 http://ppa.launchpad.net/morphis/anbox-support/ubuntu focal Release
404 Not Found [IP: 2001:67c:1560:8008::15 80]
Hit:8 http://security.ubuntu.com/ubuntu focal-security InRelease
Hit:9 https://debrepo.freedownloadmanager.org bionic InRelease
Reading package lists... Done
E: The repository 'http://ppa.launchpad.net/morphis/anbox-support/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.
it gives me the error
That particular repository does not have a release of anbox-support for Focal Fossa. It may have had one for Bionic Beaver but has not been updated. You can force it using advice from this link but it is not recommended by me.
However this worked! (see comments below)