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I have had to give up trying to use thunderbird as it constantly hangs for ages or completely freezes and is frankly unusable. Tried both the system and flatpack versions and it is the same.

Is this a known issue and are you doing anything about it?

It looks good if only it would work!

Can you offer any advice?

Geoff

PS full version is 1.153.6.0esr+linuxmint1 but the dialog box will not accept it.

159.91 has crashed my fire fox tabs will not open bookmarks will not open know because it happened immediately when update finished fix chis please if i didn't have duck duck go as a separate browser i would be in very serious trouble you are about to lose a 16 year customer ! already tried clearing cache in about support . right now only thing working is get help also ideas Mozilla not working

I've tried to use Firefox 3 times this morning. Each time I get the message that it isn't responding and my whole laptop freezes. Each time I've rebooted but the problem is still there.

Each time this happens there has been an update that I've manually dismissed. I'm backing up every day now in case I lose anything when there is an update.

Is there anything more that I can do

Is there anything I can do that doesn't involve trying to open Firefox\/

Hello, I am experiencing repeated freezes in Thunderbird 153 ESR on Windows 10. I have been investigating this problem since mid-October 2026, but have not been able to identify the cause. Thunderbird is essential for my daily work, so I would appreciate advice on identifying the cause and restoring stable operation.

1. System environment - PC: dynabook R63/B - OS: Windows 10, 64-bit - Thunderbird: 153.6.0esr, 64-bit - Mail provider: @nifty (Japan) - Incoming mail: POP3 over SSL/TLS, port 995 - Security software: Super Security (Japanese security software) - Mail storage: Local mbox files

2. When the problem started Thunderbird worked reasonably well until September 2026. The freezing problem began around mid-October 2026. Windows Reliability Monitor recorded Thunderbird as "Stopped responding" on October 19, 2026, at 9:48 a.m. This is the earliest recorded incident I have found, although the problem may have started earlier. Thunderbird update history: - September 18: 153.3.1esr - October 1: 153.4.0esr - October 14: 153.5.0esr - October 21: 153.5.1esr - October 28: 153.6.0esr The first recorded freeze occurred after the update to 153.5.0esr. However, I have not established that the update caused the problem.

3. Symptoms Thunderbird becomes unresponsive and usually has to be forcibly terminated. During these freezes, Windows Task Manager often shows Thunderbird using approximately 30–40% CPU, repeatedly around 39–40%. Freezes also occur when Thunderbird is using only about 1.1 GB of memory. On other occasions, memory usage has increased to approximately 2.56 GB. The problem occurs under several different conditions: 1. During manual POP3 mail retrieval. 2. After repeated manual mail retrieval operations. 3. Approximately 30 minutes after a single mail retrieval, even when Thunderbird is left idle. 4. Sometimes after replying to messages or copying messages to other folders. 5. In both normal mode and Troubleshoot Mode. 6. Sometimes during the first mail retrieval after starting Thunderbird. Other Windows applications generally remain responsive when Thunderbird freezes. Restarting Windows sometimes restores normal Thunderbird operation temporarily, but the problem returns.

4. Troubleshooting already performed I have already tried the following: - Reinstalled Thunderbird from the official website. - Created a new Thunderbird test profile. - Disabled extensions. - Disabled hardware acceleration. - Disabled global search and indexing. - Removed all active Thunderbird message filters for testing. - Disabled the anti-spam component of Super Security. - Disabled automatic mail checking and automatic downloading. - Tested manual mail retrieval in Troubleshoot Mode. - Reduced the size of the Inbox from approximately 4.1 GB to 2.4 GB. - Performed a full antivirus scan, which detected no threats. The new profile initially worked, including several successful POP3 retrievals, but the freezing problem later returned. Reinstalling Thunderbird did not resolve the issue. The anti-spam component remains disabled for testing, but the problem continues.

5. Windows error records Windows Reliability Monitor recorded Thunderbird as unresponsive on October 19, 2026, at 9:48 a.m. Windows Event Viewer also recorded an Application Hang, Event ID 1002, on October 30, 2026, at approximately 4:23 a.m. The affected executable was thunderbird.exe, version 153.6.0.0. These records confirm the application hang but do not identify its underlying cause.

6. POP3 communication Earlier POP3 logging confirmed that Thunderbird connected to the @nifty POP3 server and received a CAPA response. However, I have not identified which POP3 or internal Thunderbird operation was active at the exact moment of the freeze. I have not collected a process memory dump.

7. Potentially related Mozilla bug reports I found two reports that may be relevant: - Bug 2080699: POP mail retrieval becomes unresponsive in Thunderbird 153.4.0esr. - Bug 2031744: Freezing potentially related to mail index (.msf) files and background processing. Some symptoms are similar, but I cannot determine whether they have the same underlying cause.

8. Questions I would appreciate advice on the following: 1. Are there known POP3-related freezes or high-CPU problems in Thunderbird 153 ESR, particularly after the October 2026 updates? 2. Could background mail processing, folder maintenance, or mail index files explain a freeze that occurs while Thunderbird is idle? 3. Could interaction with antivirus software or Windows networking components cause these symptoms? 4. Are there diagnostic steps that can help identify the cause without repeatedly freezing Thunderbird or risking existing mail data? 5. Would this information be more appropriate as an additional comment on an existing Bugzilla report or as a separate bug report? I have already spent considerable time testing different configurations. I would prefer to avoid repeating tests that have not helped. I have a backup of my Thunderbird profile and would like to preserve my existing mail data.

Thank you for your assistance.

I'm running 153.6.0esr on Windows 11. I recently signed up for Fastmail (using IMAP) and since adding that account, Thunderbird crashes ~90% of the times I open it - just perma hangs before it can ever show all my mailboxes. This is curious because I have a different IMAP account (different email provide) that has never caused this behavior. Starting in Troubleshoot Mode doesn't help.

I tried checking off "Check for new messages at startup" on that account, but whenever I try to load Thunderbird, I can see it stuck (in UI text at the bottom) checking Fastmail servers...

Occasionally I get lucky and Thunderbird does load ok, I can then use it ok. But even in that case when it can load, *sometimes* it loads my Address Book, but sometimes it thinks my Address Book is empty.

Fastmail would only advise me that I might have a corrupt Thunderbird profile. Fine, I guess I'll try making a new profile, but I have a few questions:

1.) What might have caused this corruption? Clearly it was something about adding a new Fastmail account (whether Fastmail specific or not). Is it possibly something to do with Address Book? Is there some other fix I should try?

2.) Even if a new profile works, how do people usually deal with importing other old accounts? I have a number of big old POP accounts and I need to have all that email around to reference. Do I just try copy and pasting those mailboxes into the new profile?

Thanks.

I’ve tried restarting my phone, closing everything out, updating my phone etc, and the crashing keeps happening. It occurs on different webpages, in different places etc, and I can’t figure out how to stop it. It only started after I downloaded the latest update.

Since 2 day when I attach a document always unknown software aception (0xc0000417)on place Ox00000000501

NVIDIA Systemsteuerung nicht gefunden pops up I dont wont KI on my computer

Hello. I am back again with the same issue that I presented on the forum post three months ago. https://support.mozilla.org/en-US/questions/1594903?utm_campaign=questions-reply The difference is now it is happening on Firefox v157.0.1;everything else is identical. Qubes os R4.3.2 with Firefox 157.0.1 in a Fedora 44 xfce VM. To recap I open one window for Proxmox Datacenter Manager and as soon as I click to sign in Firefox completely disappears. I can open this in Chromium browser and Firefox ESR v.140.17.0 esr perfectly fine. Please consult the original post for all I did to troubleshoot this. I am working with the esr version now but would like to help put this issue to bed. Community members stepped up last time to help me so I am here to do my small part for others. Ask for any info you need and I'll reply ASAP. Thanks in advance. SDS

On Thursday 3rd September 2026 Firefox stopped working. I tried lots of things to get it to work to no avail. Today, 8th September 2026, I had already deleted the Firefox that was already on my PC so I downloaded a fresh copy from the Firefox website and installed it. It ran perfectly for about 30 minutes then I shut it down. 5 Minutes later, a Firefox crash report appeared which I duly sent of. Checking Event Manager a string of error messages saying the same thing, Its the XUL.DLL file that keep crashing! This was the same file that caused the failure last week. I had made sure that XUL.DLL was not on the pc when I downloaded Firefox today. When I click on the Firefox icon it open but stays on a black lower half of the screen and boxes at the top, white lined but black and transparent lines moving left to right across them, eventually it fails and closes, after a few minutes it send the crash report. Its a shame because I have used Firefox for many, many years and now having to use Edge!!!!

1. I have Edge on Windows 10 where I use hotmail account

2. Default Browser is Firefox with DuckDuck search- I also have Motzilla (here my possible confusion)

3. I use Gmail (Google)

4. I use several other app/sites through Firefox+Duck Duck

I get interference with Firefox closing down which appears as Edge MS opens a page automtically. This happens also when I am using sensitive info on secure apps.

What should I do or not do what is the interference andd Firefox Closing for. Please advise

I am sick & tired of Thunderbird email crashing. It has got so bad that I can only answer one message before it crashes again. It is useless at the moment. Help please.

Starting over the weekend, I have been unable to load my Thunderbird messages, it just says:

Home - Mozilla Thunderbird (Not Responding)

I wait, but it doesn't load.

Could I have too much stored in my email folders on my pc?

What can I do to get it to work again on my pc?

Online web browser works.

Does FF have a maximum number of windows / tabs that can be open at one time? I use 12 workspaces each with multiple windows / tabs in them, roughly guessing ~100 windows and ~8-50 tabs per window

FF randomly hangs / crashes 1-3 times a day for me and has been for some time (over multiple revisions of FF; currently 157.0.1) requiring restarting FF

System: Large workstation, 128G memory, i9-7920x (12c / 24T) Linux, OpenSuSE Leap 15.6 FF source from FF repos, not OpenSuSE

Any settings I need to change to prevent the crashes?

Cześć Problem polega na tym że Firefox nie potrafi przejść do końca logowanie do różnych stron przez Google . Pojawia się ekran wyboru konta idziemy dalej a nagle Firefox się zawiesza. To samo na Chrome działa bez p problemu. Jest to uciążliwe.