I think you need to remove the password, as the password for Thunderbird must be unique and not the same one you use for online. To remove passwords, go to tools>settings>privacy&security and delete the lines for incoming and outgoing server and then reconnect.

There are no passwords stored in Thunderbird. I also tried to create a new application password for e-mail in Google and use that in Thunderbird, but that didn't work too.

Here are the basics:

- change your security authorization to Oauth2 (do this for the incoming server settings and also for the Outgoing (SMTP) server - two places - I think you've already done that. - remove the password entries for the account (remove the entire entries both incoming and outgoing) - that password info is at Tools>Preferences>Privacy&Security - click 'saved passwords' Then click 'show passwords' then highlight the rows with incoming and outgoing gmail servers and click DELete. - check to ensure that TB is set to accept cookies (that setting is just above the Passwords section) - Google will then step you through the authentication process for your PC.

Let me know results.

This didn't solve the issue. See the settings applied in the attachment. I still got the screens to log into gmail, then a 2 step verification confirmation and then the message that connecting to the server wasn't possible.

Now with attachments

I don't recall needing two-step at that point. Instead, I recall Google giving a password. I have no idea what the issue is. Maybe someone else on this forum will see this discussion.