JoeSam said

Thunderbird has been work with gmail since 2014. I downloaded my e-mails from gmail to Thunderbird two weeks ago and turned off the PC while on vacation. I come back from vacation, turn the PC on and open Thunderbird. I get the following message when trying to download e-mails. Sending of password for user joesamabq@gmail.com did not succeed. Mail server pop.gmail.com responded: Web login required: https://support.google.com/mail/answer/78754 I have changed nothing in Thunderbird. I checked I have the latest version of Thunderbird. I have changed nothing in my gmail account. What happened? How do I fix this?

UPDATE!

I fixed the problem. I had to change the security setting in gmail to Allow Less Secure Apps. After I turned that ON, Thunderbird worked. Must be something new from Google.

No not new, but you might discover gmail asking for password to verify on occassions.

I learned about setting Allow Access to less secure apps. Unfortunately, having set googgle to allow access (it was disabled by "default") I still am not able to ready messages. I can read messages with MailWasher (my SPAM filter).

I also changed my email (per an earier article to recent...@gmail.com. Still unable to read message that I know from MailWasher and IMAP gmail access exist.