your distribution has chosen to use sand-boxed flatpaks. You need to come to terms with the limitations and settings for this flatpak distribution process as it affects ALL programs, not just Thunderbird, or use another distributions files like DEB packages. Going backwards in Thunderbird to fix issues with this release of your operating system is rather futile.

Better to file a bug report https://bugzilla.mozilla.org/enter_bug.cgi?product=Thunderbird

Matt: Why would Tbird adopt such an ineffective methodology? A simple archive of all the distributions would be the method to use. Unless you are implying that Ubuntu version is what broke the code.

Wayne: Have already uninstalled - Tbird not making friends.

Found a .deb package here for the version: http://us.archive.ubuntu.com/ubuntu/pool/main/t/thunderbird/ Version 90.1.2 appears to be the version on another box that worked back when I installed.

Got this when I tried to use Gdebi to install Tbird 91.1.2 .deb file suppose this is what you were talking about.

You will have to download thunderbird-dbg from the repository you linked to BEFORE you can install Thunderbird itself. You may find there are other things you'll need to track down too.

A better bet would be to get it from https://archive.mozilla.org/pub/thunderbird/releases/91.1.2/linux-x86_64/. Choose the language you want and click that then thunderbird-91.1.2.tar.bz2. That is a tar achieve file so when it's downloaded open it and you'll find a folder called thunderbird. Copy that wherever you like. To run it either open that folder with your file manager and click the file called thunderbird. You can also add a custom launcher for it to your menu and/or panel.

I will fill out a bug report if someone confirms I am not in error here. Installed current version again to verify I'm not doing something wrong.

-1-When I hit sent receive up pops the prompt for the account credentials of the 1st image. I OK the access requested

--2- Up pops the 2nd window shown below in which only am I not given the option to press ahead in spite of "possible risk ahead" I can not edit the URL in the address bar.

The problem is finally resolved and might be what is considered a bug or not. I found this page:

Thunderbird login to Gmail with OAuth2 fails with "secure connection failed" – how to complete the login? https://superuser.com/questions/1722267/thunderbird-login-to-gmail-with-oauth2-fails-with-secure-connection-failed-h

Summary: One guy had Apache2 another had nginx on port 80 and both caused the problem I had.

Winning Line of Effort

   Install latest Thunderbird
   Install net-tools – in order to be able to run netstat command
   sudo netstat -plant | grep 80   –  to see what is hanging out on port 80
   Saw nginx on port 80
   sudo systemctl stop nginx

   this time when I entered the credentials and gave permissions there were no problems and setup completed

The problem is finally resolved and might be what is considered a bug or not. I found this page:

Thunderbird login to Gmail with OAuth2 fails with "secure connection failed" – how to complete the login? https://superuser.com/questions/1722267/thunderbird-login-to-gmail-with-oauth2-fails-with-secure-connection-failed-h

Summary: One guy had Apache2 another had nginx on port 80 and both caused the problem I had. Winning Line of Effort

1. Install latest Thunderbird
2. Install net-tools – in order to be able to run netstat command
3. sudo netstat -plant | grep 80 – to see what is hanging out on port 80
4. Saw nginx on port 80
5. sudo systemctl stop nginx

This time when I entered the credentials and gave permissions there were no problems and setup completed

Now you can try 128 that has been released while you laboured.

Would this be considered a bug? should I file a bug report?