So, you're posting to say you don't need help. Then I wonder why post at all. Toad-Hall is one of the most senior and experienced personnel and could have helped your situation. The time will come when you must upgrade, and you dismissed that assistance. Anyway, I wish you well.

                                       or
                                             how to stop tb 91 updating to 102 despite action taken

    uninstalling102 reinstall 91 every few days is not a reasonable solution.
  toadhall solution must work for the many..........not for me.........why?

no you misunderstand..........i need help ...with authentication error tb 102 or how to stop tb 91 updating to 102 despite action taken uninstalling102 reinstall 91 every few days is not a reasonable solution. toadhall solution must work for the many..........not for me.........why?

Stopping updates is not something I am willing to discuss. It can be done in corporate situations, but for a general user the security risks related to doing so outweigh the satisfaction of doing it your way. Sadly your [https://support.mozilla.org/en-US/questions/1385462 other topic on the same question] contains more relevant information, but I will be locking it. Duplicates simply waste time. But I will quotye it here ''<p>alphapud [[#question-1385462|said]]</p>'' <blockquote>windows 10 thunderbird 102 does not work for me..........authentication error for gmail.........hve tried many times. reverted to thunderbird 91.10..........no problem.......works perfectly. copy/paste password etc for TH102 so no errors. </blockquote> Just a wild guess, but I think as you mention Gmail. This support article probably contains all the relevant information. https://support.mozilla.org/en-US/kb/automatic-conversion-google-mail-accounts-oauth20 Although if that does not solve it, then I suggest you try the standard diagnostics. *Restart Thunderbird with add-ons disabled (Thunderbird Troubleshoot mode). On the Help menu, click on "Troubleshoot mode". If Thunderbird works like normal, there is an Add-on or Theme interfering with normal operations. You will need to re-enable add-ons one at a time until you locate the offender. *Restart the operating system in '''[http://en.wikipedia.org/wiki/Safe_mode safe mode with Networking]'''. This loads only the very basics needed to start your computer while enabling an Internet connection. Click on your operating system for instructions on how to start in safe mode: [https://support.microsoft.com/en-us/help/12376/windows-10-start-your-pc-in-safe-mode Windows 10], [http://windows.microsoft.com/en-us/windows-8/windows-startup-settings-safe-mode Windows 8], [http://windows.microsoft.com/en-us/windows/start-computer-safe-mode#start-computer-safe-mode=windows-7 Windows 7], [http://windows.microsoft.com/en-us/windows/start-computer-safe-mode#start-computer-safe-mode=windows-vista Windows Vista], [http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/boot_failsafe.mspx?mfr=true" Windows XP], [http://support.apple.com/kb/ht1564 OSX] ; If safe mode for the operating system fixes the issue, there's other software in your computer that's causing problems. Possibilities include but not limited to: AV scanning, virus/malware, background downloads such as program updates.