I read this and have a number of gut reactions.

Anyone suggesting a reinstall will fix something is saying that integration with the operating system is the issue, as that is all that is affected by a reinstall. While it actually does something with most Microsoft products it does nothing for Thunderbird.

Failure to save the password with the setup simply enforces a setup that may or may not work. If this does work, then there is an issue with other software on the system. Generally this is the antivirus/Firewall

Finally your solution. This also indicates you have issues with Third party software. Probably the same Antivirus/firewall that causes issues with account setup. It does not recognize the current version of the software so locks it out. Old versions are in it's "known good" list. Unfortunately Thunderbird can do nothing to force these products to not interfere, or to not block Thunderbird access to the web.

Generally you will see folk suggesting restarting the operating system in safe mode with networking. This is a backhanded method of getting these products off the system so the setup can actually complete without being crash tackled mid setup.

Fundamentally two factor authentication can not work with a mail client. That is why oauth is now used. Thunderbird does not stop and wait for a text message and the code to be input. It asks for a password and uses it. Personally I suggest folk either use an application password or oAuth, two factor authentication really only works with a web page, not an application which initiates new connections every few minutes. When setting up, disable two factor authentication.

Generally folk blame the messenger. Thunderbird does not work, hence it has a problem. I have been around Thunderbird support for around 10 years and the number of real Thunderbird bugs in account setup can probably be counted on two hands really in that time. Buggy anti virus products. Dud firewalls, folk using VPN's and IP V6 issues. They all out number genuine Thunderbird issues like 100 to 1. I have no idea how to fix that, or any of the many other problems caused by security software. Other than to recommend to folk to use only that which comes with their operating system. My life using Thunderbird has been pain free using only Microsoft Defender.

Hello Matt,

Thank you for your reply. Good thoughts but it does not answer my question: Has something changed around version 102 in the way new accounts are added? Like the new account setup wizard? If the answer is 100% absoutely NO change in that area from say 91.13.1 to 102.6.1 then I would agree it MUST be something else. I know that 91.13.1 works OK for me, 102.6.1 does not. I don't know why firewalls, anitvirus, IP v6, would change behavior between the 2 versions. Generally, from my experience when things stop working I go back and look at what changed last and COULD it be related somehow. This issue appears to happen even on two different devices. Yeah, this is the first time I've ever had an ANY issue with Thunderbird. If nothing else I have documented my problem and provided a possible working solution for anyone else that comes across this.

I attempted to install Firebird on my girlfriends new laptop (Windows 10) several times without success even with the firewall and anti-virus turned off. It appears I may have to use an older version of Firebird. As described in the original complaint, everything goes well with entering the settings but refuses to recognize the password.