W:Updating from such a repository can't be done securely, and is therefore disabled by default., W:See apt-secure(8) manpage for repository creation and user configuration details., E:The repository 'http://security.ubuntu.com/ubuntu disco-security Release' no longer has a Release file.
I get this error message when trying to use the upgrade screen. I'm updating from 19.XX. Machine is a Gigabyte MB - B450M-ds3H AMD® Ryzen 3 2200g with radeon vega graphics × 4 AMD® Raven Graphics Gnome 3.34.2 Memory 3.14 gb