I turned off 2fa on my google account but the problem persists.

Remove your non windows defender antivirus and try again.

I used to tell people to disable antivirus, but some of the products are worse that the malware when it comes to actually disabling themselves. They say they do it and don't.

You can also use the operating system in safe mode with networking to remove antivirus and a loads of other startup problem makers like ccleaner, but most folks these days have a bargain basement WiFi connection to the internet that simply does not work in Windows safe mode. Only wired internet works with windows safe mode.

I don't have any antivirus other than windows default windows defender.

Run through a few checks...

1. Check Firewall Exit Thunderbird Access Firewall Thunderbird program must be set up as an allowed program.

2. Check for a VPN Please check to see if you have a VPN enabled. Servers do not like VPN and may block access to server.

3. Check - localhost If you have anything using localhost such as Apache Xampp (people use it when managing websites) then you must switch it off until oauth is set up.

4. 2FA and app generated password In gmail - Switch off 2FA and do not use an app specific password you may have generated. The password when requested is the normal one you use to access webmail.

5. Check cookies are enabled You must have the following : Thunderbird

• Settings > Privacy & Security

Web Content

• Select 'Accept cookies from sites'
• Accept third party cookies 'Always
• click on 'Exceptions'
• Add this as an 'allowed' exception : https://accounts.google.com
• click on 'Save Changes'

Whilst in that area make sure to delete any passwords that have been previously saved for that gmail account. You do not want any to get used whilst setting up account. Otherwise gmail may expect eg: an oauth password so will reject the normal password when setting up account OR if an app generated password has been saved, it will also confuse gmail - so check - remove all saved passwords for that gmail account.

• Scroll down to Passwords section
• click on 'Saved Passwords'
• Click on 'Show Passwords'

If you get a 'Windows Security' window asking for password - enter the same password you enter when you start computer and logon to User Account to see desktop etc. It's not talking about a mail account password.

• Completely remove any password to do with that gmail account - imap:// or smtp:// or oauth://
• click on 'Close'

Then restart Thunderbird. Create a new mail account.

• New > Existing mail account
• Enter name, email address and normal password (same password you use to access gmail webmail account)
• Click on Continue

Server settings should be auto located - imap will get chosen by default and set up to use OAuth2.

When you click on Done You should be prompted by gmail to allow Thunderbird access which you need to complete.

Please report back on results.

I added thunderbird to the windows firewall. I don't have a vpn I don't have anything using localhost I verified cookies are enabled There are no passwords saved under saved passwords

Still have the same issue.

When I try to add the account, it opens the google window telling me thunderbird wants access to my google account. I click allow and it takes me back to the account setup screen with the yellow error "Unable to log in a t server. Probably wrong configuration, username or password." I am never prompted for my password. The only time I used my password is when I set it in the password field of the account setup screen.

One thing to note, I guess my computer has some sort of "passkey" for google? could that be part of the problem?

I removed the passkey just in case, but the problem still persists.

I am a Linux user, but the results may translate to Windows as well. I tried for the last 3 days to add on 2 new accounts with no success. The resolution that I found that worked was to go into Settings > Privacy and click to allow Cookies from websites. Save that and go back to the main screen. Setup the account using the New Account setup. I am using IMAP on the default server. Prior to that, every attempt would give me a failed to connect to server message. Once the account is setup, you can shut off Cookies again with no other issues. Again, I am using the Linux version: EndeavourOS Linux x86_64 using Kernel version 6.12.17-1-lts.

as I mentioned, cookies are enabled.

I just set up thunderbird on my laptop. Added my gmail account there. It popped up the gmail sign in and actually prompted me to log in there, which I did, then prompted me to allow thunderbird access to my gmail account which I accepted. once done, the account was set up correctly with no problem.

So on my PC the problem is for some reason, when I try to set up my gmail account, I am never prompted to LOG IN to my gmail account in the google popup. it goes directly to the allow thunderbird access to my gmail account page.

Glad you were able to get it connected. I looked up other's that have issues getting the authentication, and it looks like there can be issues with the OAuth in advanced settings being setup wrong initially, not a user fault. So it may not be pulling in the right setup for POP3 or IMAP for you in auto setup. I saw where someone had to change it so that incoming was set to OAuth and outgoing is set to OAuth2. You might try going into advanced setup, and manually have it map the connection. There is a button that will let you map the server connection. With cookies on, it should in theory give you the Google account authentication screen on your PC. If you have a firewall running, it may be blocking the port needed for that connection. I would also click cookies on and off, just to make sure it recognizing the option. Best of luck!