First, I have had regular success in the past from Majorgeeks, but since the official version is at thunderbird.net, please use only that URL for Thunderbird releases. If all is working well, there is little incentive except for new features you may wish. If you upgrade, I do encourage doing a backup of profile (with thunderbird not running) prior to the upgrade.

David, thank you for your response as it was just what I needed to know. I had checked the official Thunderbird site but it did not have the 128.2.0 version yet (seems odd that MajorGeeks has it first). My only reason for considering the upgrade was that there might be some important security updates or improvements. Since I don't know of any new features I might need, I will stay with the current version. Thanks again for you quick reply

This is why I specified the official site only. 128.2 has NOT been released, which means Majorgeek has an unofficial and unsupported version. You would have had an installation with no upgrade path.

I had checked the official Thunderbird site but it did not have the 128.2.0 version yet (seems odd that MajorGeeks has it first).

No they did not have it first as they just jumped the gun in claiming it is released simply because it is on the cdn waiting for official release on https://thunderbird.net. You can get it at https://archive.mozilla.org/pub/thunderbird/releases/128.2.0esr/ for example.

MajorGeeks has been notorious for jumping the gun on Firefox releases in the last couple decades, especially in the earlier days. I caught them many many years ago posting a random Nightly development build of Firefox as a Release and instead of removing that listing they just renamed it as a release candidate build at the time *face palm*.

Don't upgrade! I just upgraded to Ubuntu 24.04.1 LTS and Thunderbird 128.2.0esr can't find my email. The files are still there, but Thunderbird can't seem to find them. I'll report back here if I find a solution.