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Sometime ago, Thunderbird stopped being able to connect with my GMail and Hotmail email accounts. I guess this had something to do with the change to OAuth authentication. I then switched over to Yahoo accounts which worked perfectly until last night when I installed the latest update, i.e. 153.0.1esr (Meadow). Now, I cannot connect with ANY account whatsoever. Thunderbird just stopped working in my two Windows 10 laptops and it does not seem to work on the Windows 11, either, although I have only tried Gmail accounts on that one (without the update), as I cannot possibly be left without an email handler.

If I try to download my emails, I get a screen that tells me that I should “Turn-off ad blockers“ and “Enable JavaScript“ in my browser, but I have tried several (4) browsers as default with the same result. I don’t have either ad blockers or cookie restrictions in any one of them and JavaScript is enabled in all (it is now by default).

I have downloaded and installed “eM Client” and it works *perfectly*. However, I would loathe to have to abandon Thunderbird and get used to an entirely new program, but which is what I will have to do if this thing is not resolved ASAP.

As mentioned, I think there has to do with the OAuth authentication system.

I have even tried ChatGPT, without success!

And there is no way to revert to the previous version !!!!!

Please do something NOW, or it is, regrettably, goodbye Thunderbird!

Was working OK. Now, "No Apps Available" appears when I try to connect to the Yahoo mail server. The "Find more in Software" button causes the "Failed to start software" message to appear. The reinstall is from the App Center.

It also opens the following link on the Firefox browser which displays a blank page. https://api.login.yahoo.com/oauth2/request_auth?response_type=code&client_id=dj0yJmk9WVZUaWRNUUZSQTBNJmQ9WVdrOVNqbHJUMGhtTkU4bWNHbzlNQT09JnM9Y29uc3VtZXJzZWNyZXQmc3Y9MCZ4PTgz&scope=mail-w+ycal-w+sdct-w&state=AUCYywsENF9wWMx1nhJAefu3yJtqIlLxOCP9laluGgA&code_challenge_method=S256&code_challenge=BhhyhkNZvKm5SUrRFTxgmp3HR7vX26vggsjMoThl4wk&login_hint=randylh%40cox.net&redirect_uri=net.thunderbird%3A%2F%2Foauth%2Fyahoo

Everything has been fine for several years but this morning I now get error: TB could not connect to server mail.twc.com, the connection was refused. Spectrum says everything is good on their end. What do I have to do to "fix" Thunderbird? I can't send or receive any emails from 5 accounts with Spectrum and the emails are there when I log in at WebmailSpectrum.net..

The issue has been "An error occurred connecting to mail.mediacombb.net:993." on the server page, where you can "test connection to server" in Account > Server Settings > Security Settings. I get the same error message for each four different accounts. I have no problems with the other two different accounts not associated with Mediacom (MC). I contacted MC and they said my settings were correct and to contact TB. I have read several posts with no real solutions except that was resolved through an update. I plan to switch to a different Linux distro later. I am currently using Big Linux Manjaro with the latest update. Note that I had no problems with TB until last month. I do not do the uninstall/reinstall apps unless it will resolve my issues as a last resort. Second, sometimes I receive MC e-mails and did not run the "test connection to server," then until today while troubleshooting for several hours. I was trying to send out an e-mail, which I had no problems last week. I already went to Account > Server Settings > Advanced and changed the "Maximum number of server connections to cache" from 5 down to 1 with no luck.

  The e-mail server settings are:

imap.mediacombb.net 993 SSL/TLS Normal Password and smtp.mediacombb.net 587 STARTTLS Normal Password They have not been changed since I switched from windows 10 to Zorin 18 to currently Big Linux Manjaro. I attempted to locate a method to check if the server settings were correct via Terminal. M$ Outlook has a test page that you can send to yourself or another e-mail account. Last, MC tech informed me that M$ Outlook is more friendly than TB. I know that I have used M$ Outlook for years and rarely had any connection issues unlike TB. Unlike Evolution, which was my first after M$ Outlook, TB is much better and easier than Evolution. Thank you in advance for your time and advice.

I still use Thunderbird on an old desktop and for the past month or more, I've discovered with some sort of communication error or the direct pop-up that I cannot login to server and it asked me to 'retry'/'Enter New Password"/"Cancel" and it's beyond frustrating. I'm on the verge of just uninstalling this for my emails and use another platform. Before so, since I've been using TBird for a long time, I figured I'd consult some experts here to guide me how to navigate this annoyance. ANY suggestions would be appreciated. Thank you.

Please see attached image of the problem.

I have tried looking on Google for ideas but have not found anything on this or how to fix. Hope someone can please help would be amazing!

Google -

400. That's an error

The server cannot process the request because it is malformed. It should be retied. That's all we know.

Has anyone had issues with Thunderbird sending and receiving email? I can only send or receive when my wifi is turned off on my phone.

I've tried deleting the app and resetting all network settings on my Android phone but still no joy.

Hello, from time to time my Thunderbird on my desktop PC running windows 10 doesn't receive emails, while they arrived on my I Phone 8. Checked my Telstra web mail, all emails are there so what is stopping getting to my desktop PC? I thought the Thunderbird receives emails than synchronize with my I Phone? As you can see from my 2 images the Telstra is up to today as is my I phone But Thunderbird is 3 days beyond. Tomorrow it may back to normal or the next day? I am returning to this message the next day 16/06/2026 1 more message on my I Phone, still nothing on my Thunderbird.

An other problem I get with Thunderbird is that a message appears on the right bottom of my screen: "Mozilla Thunderbird Connection to server mail.bigpond.com timed out" and/or "failed to connect to mail server imap.telstra.com" If I try to send an email after the above notifications, I get the "Connection Refused". I know than to just walk away. I am using Starlink as Telstra here doesn't work as I am on the fringes of Melbourne in a BLACK HOLE. Any help will be gratefully received. Thank you for reading this. Regards Ilio Pieroni

I have four different email accounts. A week ago, all incoming and outgoing traffic suddenly stopped . Webmail works normally. I have no viruses, trojans, etc. I deleted one of the accounts and tried reinstalling it. I can't do it anymore. The system keeps responding: "Unable to authenticate to the server. Username or password configuration may be incorrect." But they are all abolutely correct. I don't know what else to do. Any clue? Thanks

My name is Barrie Johnson. I have been a Mozilla Thunderbird user for my e-mail services for many years. In the past couple of days I have been getting messages from Google telling me that my e-mail provider - i.e. Mozilla Thunderbird - will not allow Google to access it, with the result that I cannot get to a current version of my Inbox and there is no trace of my calendar details. Can you please help me?

Hi. I have a Dell Inspiron, it’s a few years old, and my computer is running windows. Today I was on a website, doing my assignments as usual when randomly the internet stopped working on the browser (I was on the web for about an hour before this). There was no change to my behavior, I had been on the same site for the whole hour, and had been interacting with the site during that time. My computer still says it’s connected to the internet, and I was even able to play an online game on my computer that I had downloaded, so it looks like my computer is connected to the internet. I’ve tried to clear my cache and open private windows but that didn’t help.

I'm on a private home network with an internet connection. When I try to use Firefox it displays a message saying "You must log in to this network before you can access the internet".

Many websites, e.g. Amazon, won't load and an 'Open network login page' button is shown. When I click this it takes me to a Mozilla page talking about Captive Portal, but there's nothing about how to stop this happening and access those websites.

Other browsers, e.g. MS Edge, or Brave, have no problem access these websites.

How do I fix this problem?

I am trying to be nice but it's should be going both ways . Server Not Found. Firefox can’t connect to the server at www.rebaid.com. AND YOU GIVING ME ADVICE: "Try connecting on a different device. Check your modem or router. Disconnect and reconnect to Wi-Fi." We both know that my router is not the problem nor my PC/device. It's you and you should harder to connect me with a page-site.

I am getting the error "connection timed out to connect to SMTP server". I am running on Linux Mint. The same setting do work on MacOS so there is no wrong config or broken SMTP server. It was working well since a couple of years. I also tried troubleshooting mode but still the same.

Cheers, Thomas

I have been using Firefox on my iPhone for years without problems. But for about a week now if I’m on data it can’t load any websites, a message appears saying it cannot connect to server. It works fine when I’m on WiFi.

Error code: PR_CONNECT_RESET_ERROR

   The page you are trying to view cannot be shown because the authenticity of the received data could not be verified.
   Please contact the website owners to inform them of this problem.

Afterward no mail is being received from any of the providers, everything is stopped at last time I connected before the error, i.e. 7/9/2026

I have a similar problem to others reporting a connection time-out. But the circumstances now seem different. It is getting worse. First thing today, I noticed that Thunderbird emails (current/up-to-date version) were taking several minutes to finish sending. After sending 3 successfully, but slowly, all further emails failed, as per image attached. My wife's computer, using the same email provider, etc, was working okay. I checked and compared the account setting, and they were slightly different (no idea why) so I altered mine to match the other PC. That didn't make any difference anyway. Then (a few hours later) my wife's PC started having the same problems as mine, as if it's a spreading disease. Could it be a virus? Thanks.

Each time I attempt to login w/ T-Bird, google mail gives me this message:

400. That’s an error.

The server cannot process the request because it is malformed. It should not be retried. That’s all we know.

I have been using Thunderbird for many years. I have 4 accounts that have all been set up and working fine. This morning the 2 yahoo.com accounts stopped working. I logged in to the impacted accounts using a web browser and password just fine. I then updated Thunderbird to 116.0 to see if that would fix the problem, but it did not. The outlook and gmail accounts are working fine, for now.

When Thunderbird attempts to download mail for the yahoo accounts, I get a large pop-up window with "Edge: Too Many Requests". The pop-up window is blank except for that error message. I get the small pop-up with the Authentication Failure message. Sometimes I get Retry, Enter Password or Cancel. But I never see a window that will allow me to enter my password.

I can send/receive mail from the accounts while logged in via a browser but authentication fails within Thunderbird.