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After a reboot and Windows 11 update today, Thunderbird (I believe it was v155) will not open. It asks for the password, then sits at [Not Responding].

I have copied my profiles (there are two, one dated 2023 with only a 1K .json file in it, and one created tonight while I was troubleshooting that's several GB and when copying, appears to contain all my mail folders although I can't access them directly from within the profile) to a separate location (my desktop).

I've tried the following (after checking previous questions here in Mozilla support):

(1) booting Windows into safe mode

(2) opening Thunderbird in Troubleshooting mode (Shift while opening), both in Windows safe mode and normal boot

(3) uninstalled Thunderbird from Control Panel, downloaded and installed a new copy of Thunderbird

All give the same result: "not responding", can't click anything. Can only wait or close.

I was able to disable an extension that I installed yesterday that had been working fine.

I'm also wondering if the problem is mail folders that are too large. I have some candidates for deletion but since I can't see any .msf files for them, I can't delete (because I can't open Thunderbird.

I'm leery of instructions to outright delete any Thunderbird folders/files because (1) I can't see my mail folders directly and (2) I'm self-employed and all my client and business emails are in there. Losing them woud be a disaster.

I'm tempted to try the Windows option of restoring my entire computer to an earlier point, say, this morning. But that seems like possible overkill if it's an issue with just Thunderbird.

I'm freaking out, please help!

Since Firefox does not support video calls, deaf people cannot chat with their friends in sign language on Facebook Messenger. This feature should be brought back.

When I try to go to Google's website, I get this message:

Secure Connection Failed

The page you are trying to view cannot be shown because the authenticity of the received data could not be verified. What can you do about it?

The issue is most likely with the website, and there is nothing you can do to resolve it. You can notify the website’s administrator about the problem.

Error Code: PR_CONNECT_RESET_ERROR

The same thing happens with YouTube TV. My Bitdefender also flagged it as a suspicious page.

When I open Thunderbird it is sending my emails directly to the deleted folder. I have tried all-sorts and cannot find an answer. I transferred Thunderbird to my new PC and all was working okay for a few weeks then all of a sudden there were emails missing from my inboxes and I found them in the deleted folder. I am 76 years old and need an easy step by step solution please ..... John

Доброго времени суток.

Я установил сертификаты по инструкции, которая лежит на s.sber.ru/70VQ2B . После этого не прогружается полностью окно входа на online.sberbank.ru (не видно содержимого фреймов). Проблема полностью аналогична описанной здесь: https://support.mozilla.org/ru/questions/1597415

Firefox ESR115.40 (64-разрядный, Windows 7) - страница выглядит, как на скриншоте по ссылке выше.

Установлены скачанные сертификаты в самом браузере, они отображаются в разделе Управление сертификатами -> Центры сертификации. После этого абсолютно ничего не изменилось.

Может, надо еще что-то сделать? Или на Firefox ESR115.40 вообще работать не будет? До перехода на сертификат от Минцифры России проблем не было.

I've searched & waited past few years for an Extension to make the TOOLBAR FONTS larger, none found. Reason being many of us are using larger monitors and TV's and we're usually sitting or standing further away from the screen. Problem is the font size cannot be changed, they stay small and hard to read comfortably. __YES I've reset my operating systems font size, that does not work in Firefox TOOLBARS. __Changing the "firefox/addon/theme-font-size-changer" has been eliminated by Firefox. __Changing the "layout.css.devPixelsPerPx" to a larger number increases the whole TOOLBAR. I just want the FONT size larger. __(someone suggested) NO, I'm not going to setup 2 monitors.

Sure would like this issue fixed. In the pix below, it has been done.

Thunderbird not connecting to server. It says timds out and an error occurred connecting to mobile.charter.net. I can neither send or receive emails. This started 8/20/2026

I hopped over to the ideas page because I had a couple suggestions, and found I was not alone because lo and behold someone else had the same ideas. So I decided to agree by hitting the kudos button, but imagine my surprise when instead of adding to the number of users who supported the idea, this feature only seemed to reload the page for me!

Hello, I have an issue with the history not being synced between my Android smartphone and my Windows PC/s.

History synchronizes just fine between my PCs (Win 10/11). Other sync functions between my phone and PC work just fine - checking the open tabs on another device, sending a tab to another device.

I am currently using 2 "sets" of Firefoxes on my devices with 2 different accounts, and the issue is present on both:

Set 1: Firefox - PC1 (Win10), PC2 (Win11), Phone (Motorola Edge 40 NEO) Set 2: Firefox Nightly - PC (Win11), Phone (Motorola Edge 40 NEO)

I already updated Firefox everywhere, logged out and in, cleared the cache & storage, restarted my phone etc.

Want to disable the news pop-ups that appear at the bottom right hand corner when I first open Firefox. Prevent me from printing while they pop-up and are usually quite a few of them.

Thunderbird is downloading new messages but failing to display them.

Other functionality remains active, ie I can see and open messages, delete all the contents of folders, compose and send messages, but when the software downloads new messages they simply do not display and cannot be accessed.

Not sure if it's relevant, but the message INBOX count appears to be stuck at the number 59, although more messages than that have been downloaded.

Bizarrely this is the message displayed whenever I now open the Thunderbird application (it was there when the problem first appeared and returns everytime). Out of desperation I even made a donation in the hope it would release the messages!

Thank you in advance, Steve Davidson

required platform is MacOS. In order to file a support ticket with a organization I need to send them browsing history. Sending the entire history is unacceptable. I need to be able to search Firefox history for their URLs, narrow those by date, and export just the relevant data.

I have only seen an extension to export the entire history. I need this to be a fast operation not requiring installing sqlite3 or manually editing very large html or other files.

If there is not an extension capable of doing this, then it needs to be added as a core enhancement.

About two months ago, after various Windows and Firefox updates, I can no longer make Firefox the default browser. In Windows Default Apps the only option for FF is to make it the default program for Adobe Acrobat Document. Choosing Make FF Default through the browser does not work either. Additionally, I’ tried numerous suggestions, using AI help offered by both FF and Chrome, without success.

The OS is not allowing me to make Firefox the default browser. Is there any way around this?

Any suggestions?

Firefox: 155.0.1 (64-bit) Windows 11 Pro Version: 25H2 OS build: 26200.9278

Thanks

After recent Firefox update in v 154, saved passwords do not auto-fill in all websites. Actually, not even the username is loaded. I tried to open in troubleshoot mode and didn't work too. I tried to log out and re-login and fixed for a while only. Then same issue re-occurred. In websites where I have multiple accounts it's too hard to find the proper one. In the Settings > Passwords everything is enabled.

I used Private Browsing to review a web site, and saved a couple of files to my hard drive. When I closed the Private window and went to a different page in Firefox, then used Print and "Microsoft Print to PDF", the print dialog came up with the Private window's last save location as my initial save location. It doesn't matter whether the regular Firefox window was open before or after the Private window was closed.

This was a leak from Private to Regular. Windows 11. Firefox 155.0.1 (64-bit)