Thunderbird Community Forum

I wanted to share a specific startup freeze loop I encountered today.

I had a moderate number of tabs open in Thunderbird when I quit the app. I had set up a single IMAP message filter yesterday to automatically move incoming automated text alerts into their own folder (causing about 50–60 small emails arriving in quick succession this morning at startup).

The Problem: Upon starting up, the app almost immediately choked and became unresponsive. Unlike the freeze report by another user here on August 21st.

My Workaround: After a few attempts to open Thunderbird I managed to break the freeze loop by instantly closing the single open UI window right at startup. This kept T-bird running invisibly in the macOS background. It seemed that without the need of rendering the UI, the background engine successfully completed all the IMAP syncing and filtering tasks.

When I brought Thunderbird back to the foreground, all my open tabs instantly "snapped", and the app has been perfectly stable since. I haven't tried to replicate this due to the fear of breaking the current stability.

Has anyone else recently noticed Thunderbird freezing under similar conditions lately? Let us know if this workaround helps you get past your startup freezes too!

We both ended "Bit Defender" and it somehow ruined her Thunderbird and all of it's content. She no longer has access to Thunderbird. I have a business and she is my accountant. Please help.

Been to various sites for diag info. I have uninstalled antivirus and tried it, no joy. I have done all the following to each folder - compess, repair, deleted old emails, etc. (I actually have rules that are to do this automatically). I have captured config info, uninstalled and installed fresh. Still have the problem. -- and finally restored so I still have email addresses, etc. etc. This problem has started for me with in the past 2 weeks.

1) ALSO note: I am running W11 home. Mozilla keeps calling this W10. I do not know what the difference is between Home and Pro, but I am planning to upgrade to PRO within 2 months (looking for a reasonable deal on the cost of the upgrade). 2) Wife's computer is W11 Pro, she does not have the problem.

I'm running TB on Windows 11 on a Dell Desktop machine. It's a pretty basic installation with EE Cyber security, which is I think Norton. I've been using TB for a couple of years but recently it has almost stopped working. I notice from Task Manager that TB is massively leaking memory and consuming much CPU time. I don't think I have any add-ons and I only use TB for email. It's now so bad that I'm even unable to go into TB's Settings or Tools or anything else. I've tried creating an exclusion for TB profiles and TB.exe in the Norton. I've tried starting TB in troubleshoot mode but all to no avail. I have it in IMAP, Port 993, SSL/TLS for incoming mail and Port 465, SSL/TLS, Authentication Required for Outgoing mail. I'm currently often unable to even access mail previously downloaded to the local Mail folders, TB is just hanging with the bar in the lower right corner endlessly running along. Most puzzling of all, is that very occasionally is starts working again and then I dare not switch the machine off! It's become an indeterminate system. Please help, I'm nearly eighty and trying to organize my holiday, which is needs email to make bookings. Thanks in anticipation.

I'm experiencing an issue with Thunderbird when trying to open attached PDF files. As soon as I double-click a PDF attachment, Thunderbird immediately shuts down completely. When I reopen Thunderbird and try again, the same thing happens.

I have already restarted my computer, but the issue persists. The only way I was able to open the PDF files was by accessing the email directly through Outlook.

Still having issues with Thunderbird on my Windows 11 laptop. I tried reinstalling the program but still locks up. Any suggestions or comments would be appreciated Thanks Dave

Topic: My ignorance! Working side by side with my bank account 1/2 size, and 2 columns of my inbox screen 1/2 size worked great! A job well done! Re-sizing TB screen back to normal size caused a large blank screen, headed "Inbox", with only a couple of blank columns, no folders, no Sent, no Trash, and it is unresponsive. I went out and back in and it is the same. I didn't do anything unusual. This is a fairly routine action. Please can you help?

When I try to add a new Mail Account, the "Looking up configuration" step hangs indefinitely. I have to force a hard exit to reopen the app. I was able to add my hotmail account without issue, but now that I'm trying to add @yahoo.co.uk , it just freezes up. Thx

Windows 10, newest Thunderbird.

I was using TB like normally on windows 11 when it crashed. Now every time i try to open the app it prompts me to send in a crash report, but every time i press "restart thunderbird" a new window with crash report shows up. I have tried writing a comment, checking and unchecking all the boxes and pressing quit thunderbird. But i still get sent into the loop.

Thunderbird is very glitchy and slow after the latest update - Thunderbird 140.11.1esr (20260522210329)

Especially, when I get a new email, Thunderbird stops responding for 5-10 seconds and then starts working.

I am using Windows 11

roland.multhaupt

18. Juni 2026, 07:13 GMT-6

Firebird is so slow now, that I can rarely receive the code that you send me. Have to take annother programm for that. Freezes even when trying to mark a mail or erasing it. WIN 11. The programm is working well at my wifes laptop also WIN 11. 2 month ago it worked fast and fine. Working in Troubleshooting mode does not show any spam ordner like before and it does not run better. I also downloaded the last version. No change! I would like to uninstall the programm but did not dare due to perhaps loose all my mails. Could you help me please? Thank you!

Hello, It's been a few days Thunderbird freezes when I want to save a message on the computer (save as). When I close the saving window which is not responding, it automatically saves the message on my desktop. The file where the last message was successfully saved is still existing so I don't think it is a path problem. I have tried to restart it without the add-on but it doesn't change anything. And it is up-to-date. Anyone knows what the problem could be? Thank you! Estelle

On Sunday, May 7, my Thunderbird program suddenly stopped responding (neither the shortcut nor the program itself will run); clicking on the shortcut icon or attempting to open or run the program itself causes the "loading" or spinning wheel icon to pop up, run for about 10 seconds, then stop.

I've used Thunderbird as an email client for my Sonic email account on my pc for over 8 years without any difficulties until now, and now seem to be locked out of my Thunderbird account. I cannot access it to confirm the version, although I believe it is current, since it appears to update automatically.

My Sonic account continues to function normally, but I keep (save) all incoming and outgoing emails in my Thunderbird system and now am unable to access any of those, and unable to access my Thunderbird account at all..

I've consulted with Sonic over this; Sonic maintains that any difficulty must be on my end connecting to Thunderbird, and suggested that I might have changed the account password. However, I have not changed the password, etc.

Please help asap.

Thanks, immensely.

Tim