If you start thunderbird.exe with --allow-downgrade you can bring up prior version. But backup you profile before attempting it.

Assuming you use Windows, you can usually press Windows key and 'r' key and type in thunderbird.exe with --allow-downgrade

Thank you David for getting back to me. I am using Windows 10. I never knew how to do windos R before so thank you for that tip. How do I back up my profile when I can NOT get into Thunderbird since the update ??? It does NOT open. It just gives me XULRunner error 91.10.0 is not compatible with 91.11.0. That's it. I don't know how to proceed. My apologies but I am a NOVICE when it comes to Computers.  :-(

You'll do fine, not to worry. first, open File Explorer (usually, you can right-click on the Start icon on task bar and the menu will show File Explorer). Your profile is at c:\users\YOURID\appdata\roaming\thunderbird\profiles. If there is more than one folder, only one is the desired one but for now, copy everything that is there. (YOURID is dependent on a name associated with your PC when it was first used. By itself, it is unimportant, and once you locate c:\users it will likely become obvious.)

Next, uninstall Thunderbird. Do you have downloaded copy of 91.11.0? Would you prefer the latest version, 102.0.1? It has more features, but a few bugs, but imports profiles more easily. Let me know and we'll take next steps, depending on your selection.

David - I found my profile it is at C:\users\chris'pc\appdata\roaming\thunderbird\profiles but there isn't a folder but like 13 lines of things stored there. I haven't done anything with it because I don't know what to do. Is there anyway that you can log into my pc and do the move yourself so that it is done correctly ??? I am TERRIFIED of losing my data if I do something wrong. Thank you so much for your help on this in advance. Chris

Please post a screenshot of what you're looking at there.

Sorry, you are correct. There is a folder. It is when I click on the folder that it opens and shows me 13 line items. BTW, I don't know how to do screenshots. Sorry. When I copy the folder, where do I put it ??? On my desktop ??? I am HOPELESS at this.  :-(

There is a free snapshot program at bluefive dot pair dot com. Easy to use. Create a jpg file and post it and we can go from there. Also, please confirm situation. That is, have you installed new Thunderbird 102 yet?

David - Sorry that it has taken me so long to get back to you. FYI, today I copied my Thunderbird profile from profiles to my desktop. I also used the Mozilla Thunderbird Uninstall Wizard to uninstall Thunderbird from my Computer which is using Windows 10. However, there still remains:

• Mozilla Maintenance Service 606K 6/2/21
• Mozilla Firefox (x64-en US) 208MB 7/8/22

Let me know if I am supposed to do anything with either of those before proceeding.

I have yet to re-install Thunderbird because I don't know what version to use. I will rely on your advice. I will send this off to you and reboot my computer to ensure that all the changes have taken effect and wait to hear back from you. I appreciate all your help on this since I have NO CLUE what I am doing !!!  :-(

I recommend using the most current version. That eliminates the problem of having to upgrade from 91 later. You never posted a screenshot of what you found at the ....appdata/roaming/thunderbird/profiles folder.

Hallelujah !!! I just downloaded and installed Thunderbird 102.0.3.exe as my default email and MAGICALLY all my email from Time Warner RR and Gmail is listed as I am used to. Thank YOU, thank YOU, thank YOU !!! It looks like my problem is FINALLY SOLVED !!!  :-)