I am trying to read my gmail email using Thunderbird. However, once I fill in the server configuration, I get a 2fa pop-up window with an error message. See attached.

That is not 2fa it is oAuth. Thunderbird sends your username (as entered in the account setup, usually as "your email address") this page is end by Google to complete the authentication and password entry to meet their requirements.

Why the details send are malformed is something of a mystery to me. Do you have an antivirus scanning web pages and or email? It may be the cause of your issue. Protecting you from correct operation of the signin process.

What can I do to get this to work? Or is Thunderbird unable to access gmail? Thanks in advance, Mike.

All of my email from this site comes via a gmail account through Thunderbird using oauth2.0 authentication. So for your to not be working we need to really be looking for activities outside Thunderbird. Like for instance do you use a VPN? Do you have the same issue when you turn it off.

The following link might be helpful: Google sign in for Thunderbird https://support.mozilla.org/en-US/questions/1487655

Thank you for your time and I am sorry for the delayed follow-up. I use a Linux machine and have NO anti-virus or any other kind of malware scanning in place. For the sake of testing I turned blocking off on my pi-hole instance and am still having the same issue.

I have also verified that my credentials are correct. Perhaps I need to have Chrome installed?

Any other suggestions would be most welcome!

Mike.

Right after posting my last reply, I found the answer at:

https://support.mozilla.org/en-US/kb/automatic-conversion-google-mail-accounts-oauth20

Turns out you have to enable cookies in Thunderbird. I don't even remember disabling them.

Once again, thank you for your time. Mike.