I followed the instructions, as I understood them, and had an error. I first executed sudo apt install software-properties-common apt-transport-https sudo apt update Then: mikes@studio1:~$ sudo apt-add-repository https://cinelerra-gg.org/download/pkgs/ub20 Hit:1 http://us.archive.ubuntu.com/ubuntu focal InRelease Hit:2 http://us.archive.ubuntu.com/ubuntu focal-updates InRelease Hit:3 http://security.ubuntu.com/ubuntu focal-security InRelease Hit:4 http://us.archive.ubuntu.com/ubuntu focal-backports InRelease Ign:5 https://cinelerra-gg.org/download/pkgs/ub20 focal InRelease Err:6 https://cinelerra-gg.org/download/pkgs/ub20 focal Release 404 Not Found [IP: 104.27.142.18 443] Reading package lists... Done E: The repository 'https://cinelerra-gg.org/download/pkgs/ub20 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. I've been able to compile by downloading source and then compiling locally, but had to rebuild the system in order to solve a problem with printing. I'm still at the experimenting stage, so this is not a major problem. Mike -- Michael L. Squires, Ph.D., M.P.A. 546 North Park Ridge Road Bloomington, IN 47408 Known in the SCA as Alan Culross, KSCA, OP, etc. "Michael Leslie Squires" on FB Home phone: 812-333-6564 Cell phone: 812-369-5232 www.siralan.org (personal) or www.smithgreensound.com (PA) UN*X at home since 1985