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

You may need to adjust settings in your anti virus if issues continue after ensuring cookies are enabled.

Thanks for answering Matt,

Cookies are allowed now. I checked my anti-virus and Thunderbird is allowed and is not blocked.

Can you explain what the message ‘Authentication failure while connecting to server imap.gmail.com’ refers to?

In any web browser I have no issues connecting to my gmail accounnts.

Another message is ‘The browser you’re using doesn’t support javascript or has javascript turned off’.

Thanks Again,

Mike

Use the config editor to have a look at the setting for javascript.enabled is set to true. It should be, but there are the over eager that disable it because they don't use RSS feeds and software the "saves" us from security problems. So have a look see.

‘Authentication failure while connecting to server imap.gmail.com’ imap.gmail.com is refusing to authenticate you. Probably from what you have said because the authentication sequence is not completing so you don't get and authorization token to connect with.

Basically it is saying the key you shoved in the lock is not working.

A final point, what anti virus are we talking about specifically. The big four here are Norton, Kaspersky, Avast and McAfee as regular troublemakers.

Matt,

Many Many Many thanks. You saved me from a real mess.

The javascript setting was the problem. javascript was set to false and right after I reset it I was offered the login prompt and I got to redo all my logins except one and I can fix that I think.

Just FYI: I use Bitdefender. When it expires in August I'm thinking of using another product. Any particular recommendation would be great.

Thank You for the help.

Mike Trahar