Public bug reported: When installing a fresh Ubuntu 20.04 from an USB Stick, then in the "Software & Updates" settings window, where there is a possibility to set up software sources, on the "Developer Options" tab the "Pre-released updates (focal-proposed)" checkbox is ON by default, therefore installing pre-release packages for regular users as well. And not just when booting from the installation media (USB stick), but after installing the system onto the main HDD / SSD , the situation is the same.
The issue popped up when I already had gnome-shell 3.36.2 on my system (completely killing gnome-tweaks), while the latest stable release was just 3.36.1 Thanks to #ubuntu IRC channel and especially "ioria" user to help me figuring out what is going on. The installation ISO image I was used has the signature from 3rd May. $cat /var/log/installer/media-info Ubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200503) $lsb_release -rd Description: Ubuntu 20.04 LTS Release: 20.04 $uname -a Linux sarmx777 5.4.0-31-generic #35-Ubuntu SMP Thu May 7 20:20:34 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux $ ProblemType: Bug DistroRelease: Ubuntu 20.04 Package: ubiquity (not installed) ProcVersionSignature: Ubuntu 5.4.0-31.35-generic 5.4.34 Uname: Linux 5.4.0-31-generic x86_64 ApportVersion: 2.20.11-0ubuntu27 Architecture: amd64 CasperMD5CheckResult: skip CurrentDesktop: ubuntu:GNOME Date: Mon May 18 20:06:44 2020 InstallCmdLine: file=/cdrom/preseed/ubuntu.seed initrd=/casper/initrd quiet splash --- maybe-ubiquity InstallationDate: Installed on 2020-05-11 (7 days ago) InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200503) SourcePackage: ubiquity Symptom: installer UpgradeStatus: No upgrade log present (probably fresh install) ** Affects: ubuntu Importance: Undecided Status: New ** Tags: amd64 apport-bug focal ubiquity-20.04.15 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1879373 Title: Pre-released updates ON by default To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+bug/1879373/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs