Thank you for reporting this bug to Ubuntu. Ubuntu 16.04 (xenial) reached end-of-standard-support on April 29, 2021.
See this document for currently supported Ubuntu releases: https://wiki.ubuntu.com/Releases We appreciate that this bug may be old and you might not be interested in discussing it any more. But if you are then please upgrade to the latest Ubuntu version and re-test. If you then find the bug is still present in the newer Ubuntu version, please add a comment here telling us which new version it is in. Please note: many of your web certificates are invalid on your machine unless you enabled ESM to get updates; or manually backported the updates yourself. You may find more details on this link (https://askubuntu.com/questions/1378534/update-the-certificates-on- ubuntu-16-04-tls), but please note 16.04 is now EOL unless you have ESM enabled. Support sites maybe more appropriate, eg. https://answers.launchpad.net/ubuntu. You can also find help with your problem in the support forum of your local Ubuntu community http://loco.ubuntu.com/ or asking at https://askubuntu.com or https://ubuntuforums.org, or for more support options please look at https://discourse.ubuntu.com/t/community-support/709 however do note as 16.04 is now completed it's public or community support period; you may just be told to backup & re-install; as upgrade are now more complex due to expired certificates etc. ** Changed in: ubuntu-release-upgrader (Ubuntu) Status: New => Invalid -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1961376 Title: Unable to complete Xenial to Cosmic release upgrade To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/ubuntu-release-upgrader/+bug/1961376/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs