Do you see the OAuth browser window on first connection, and enter the account (not app) password to give access to TB? Are cookies accepted in Settings? VPN? Antivirus?

Yes, I get a popup asking for my Yahoo password and asking me to agree to conditions. Yes, cookies are enabled. I am not using VPN and, since this is Ubuntu, no antivirus needed.

Oddly my wife has her own Yahoo account and that works, but her smtp is set up weirdly: It is SSL/TLS with Normal Password and it works! So I changed it to OAuth2 and it still works. Her full user name @yahoo.com is specified both in imap and smtp.

So, it is very confusing and frustrating. I am using Yahoo less and less but have not rescinded all lingering correspondents.

Perhaps post a screenshot of the exact point where it fails. I recall there were some issues with some users running a local web host that conflicted with OAuth authentication.

The popup only shows for a few seconds and not every time, unless I restart TB, so I can't get a screen shot but it says "authentication failure while connecting to imap.mail.yahoo.com". I just saw it now. I have a Vivaldi browser running with my wife's Yahoo account connected and a Firefox browser connected to my Yahoo account both running.

Here is the screenshot, attached.

Have to do something else for the next 2 hours. Will reply later.

Well, this gets curiouser & curiouser. TB works fine on my old HP desktop with exactly the same IMAP & SMTP settings. I tried the following on my newer computer: Quit Vivaldi, leaving Firefox with Yahoo and TB running. No change. Restarted FF & TB. No change.

Rebooted newer computer & shut down browsers. No change.

Here is the dump of the Troubleshooting report, truncated due to size. Application Basics Name Thunderbird Version 102.4.2 Build ID 20221101185644 Distribution ID User Agent Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.4.2 OS Linux 5.15.0-53-generic #59-Ubuntu SMP Mon Oct 17 18:53:30 UTC 2022 OS Theme Yaru / Yaru Multiprocess Windows 0/0 Fission Windows 0/0 Enabled by default Remote Processes 3 Enterprise Policies Inactive Google Location Service Key Missing Google Safebrowsing Key Missing Mozilla Location Service Key Missing Safe Mode true Memory Size (RAM) 15.5 GB Disk Space Available 742 GB Mail and News Accounts ID Incoming server Outgoing servers Name Connection security Authentication method Name Connection security Authentication method Default? account2 (none) Local Folders 0 3 account3 (imap) imap.gmail.com:993 3 10 smtp.gmail.com:587 3 3 true account8 (imap) imap.comcast.net:143 2 3 smtp.mail.yahoo.com:465 3 10 true account11 (im) prpl-gtalk 0 0 account14 (imap) imap.mail.yahoo.com:993 3 10 smtp.mail.yahoo.com:465 3 10 true account16 (imap) imap.vivaldi.net:993 3 3 smtp.vivaldi.net:465 3 3 true account21 (imap) imap.mail.yahoo.com:993 3 10 smtp.mail.yahoo.com:465 3 10 true

I uninstalled and reinstalled TB. No change.

Reinstalling TB won't make any difference if the fault lies in the separate profile folder. But to test if there's something in the current profile that's blocking the connection, try creating a new profile from Help/More Troubleshooting, about:profiles, and add one Yahoo IMAP account, with an account password that is verified by accessing the account in webmail.

I did that and selected automatic IMAP generation. Got error: Unable to log in at server. Probably wrong configuration, username or password.

I went into manual configuration and the settings are correct, as before.

So, nothing solved - but weird it works on one computer but not another.

I know you're on Linux, but there's a setting in OS X that might be relevant: Settings/General/Network & Disk Space, Connection, use 'no proxy'. Otherwise, I tend to think there's some setting or app outside of TB that's the source of the problem, since you have the same issue with a new profile and correct Yahoo settings.

Network proxy is off on my newer computer in Settings. My router has "Disable IGMP Proxying" clicked. On the older PC Proxy is Automatic. Changing proxy to automatic does not change anything and I still get the Authentication error. Restarting TB does not change anything either. Really Alice in Wonderland.

Now I cannot reconnect to gmail or Comcast from TB - getting the same auth error.

If this was a Windows setup I would recommend running Windows in safe mode. For Linux, there is Recovery Mode, but I've no experience with it as far as troubleshooting TB issues.

Thunderbird is unusable for me now. I keep on getting popups asking for my gmail and Yahoo passwords but I cannot retrieve mail. I am shutting TB down and will use webmail for the foreseeable future.

Perhaps going back to release 72 may be worth a try but I don't know how.

So, I'm giving up on TB for now and installed the Mailspring client. Gmail set up went fine.

When I tried to setup Yahoo email on it I got an authentication error again: Important: Yahoo requires that you create a unique app password for email apps like Mailspring. Follow these instructions to create one and then paste it below. https://help.yahoo.com/kb/SLN15241.html?guccounter=1

connect <mailcore::IMAPSession:0x7ffc79c31400>

• OK Welcome! IMAP Server up and ready to accept your request

ssl connect imap.mail.yahoo.com 993 2 OpenSSL version: OpenSSL 1.1.0f 25 May 2017 1 CAPABILITY

• CAPABILITY IMAP4rev1 SASL-IR AUTH=PLAIN AUTH=XOAUTH2 AUTH=OAUTHBEARER ID MOVE XYMHIGHESTMODSEQ UIDPLUS LITERAL+ CHILDREN UNSELECT X-MSG-EXT OBJECTID IDLE ENABLE UIDONLY X-ALL-MAIL X-UIDONLY LIST-EXTENDED LIST-STATUS SPECIAL-USE PARTIAL APPENDLIMIT=41697280

1 OK CAPABILITY completed connect ok login 2 LOGIN "kjaspan@yahoo.com" ********* 2 NO [AUTHENTICATIONFAILED] LOGIN Invalid credentials

Comcast: Same:

connect <mailcore::IMAPSession:0x7ffec5683b70>

• OK [CAPABILITY IMAP4rev1 SASL-IR LOGIN-REFERRALS ID ENABLE IDLE LITERAL+ AUTH=PLAIN AUTH=LOGIN AUTH=OAUTHBEARER AUTH=XOAUTH2] Dovecot ready.

ssl connect imap.comcast.net 993 2 OpenSSL version: OpenSSL 1.1.0f 25 May 2017 connect ok login 1 LOGIN "kja5pan@comcast.net" ********* 1 NO [AUTHENTICATIONFAILED] Authentication failed.

I was able to successfully create a Yahoo account with Mailspring using an app password.

Using STARTTLS, Port 143 for IMAP and STARTTLS, port 587 I was able to successfully set up Comcast, per this URL: https://www.xfinity.com/support/articles/email-client-programs-with-xfinity-email

I tried that approach with TB for Yahoo and gmail. It did not work. I got "Unable to log in at server. Probably wrong configuration, username or password.

I was able to successfully configure my Comcast account with TB using this URL: https://www.xfinity.com/support/articles/setting-up-thunderbird?

My understanding is that an app password is only needed if the mail app doesn't support OAuth2 for the mail provider, or if the account has two-step verification. But if OAuth2 is supported, as it is in TB for Yahoo, AOL, gmail and a few others, then authentication should succeed when the account password is entered in the OAuth window (if 2-step verification is also enabled, there's an additional step in the OAuth process). But I haven't seen that Yahoo requires an app password for OAuth2 when the mail client supports OAuth2. As you have discovered, gmail OAuth2 won't work with an app password. I can confirm that AOL accounts, which are based on Yahoo mail technology, work in TB with OAuth2 and the account password.

I am at the end of my wits, having tried everything. After so many years of using TB it has failed me, alas.