Forum der Gemeinschaft Thunderbird

I have been using Thunderbird for years with no problems. However recently, Thunderbird very often simply stops responding. Sometimes it just hangs up and sometimes the program bar at the top displays "Mozilla Thunderbird (Not Responding)". If I try to wait for it to respond, it literally hangs for several minutes before it begins to respond again, and often, it simply never starts responding again. It has simply gotten to the point where Thunderbird is practically unusable. All my other application software continues to work with no problems. It's just Thumderbird.

The version number in this submission may not be correct. I can't provide the real version number because of the hangups.

Any suggestions?

Was on version 115, had this problem. Updated to version 155, same problem. One of the email accounts I set up on Thunderbird is redacted1@lake48.net, registered with 123-Reg. However, this is a forwarding address and has no email server, which is why I am getting the error now.

Messages addressed to redacted1@lake48.net are forwarded to redacted2@lake48.net, which does have a server, My system was to download from there and use a rule to divert the incoming message to my redacted1@lake48.net Inbox. This has worked OK until now. Thunderbird gives me this error right at the start and then does not respond, so I cannot get in to investigate account settings, and cannot access emails in other accounts such as gmail. 123-Reg has today changed its system, assuring me I don't need to change anything. Clearly I do, but I can't get in to change it.

What should I do to resolve this? I have no other access to my emails.

Since 3rd September 2026 Thunderbird opens a system integration window and then goes to not responding. I cannot access my emails through this software at all at the moment as there's no way past his pop up. Version 153.1.1, Windows 11 Home.

Starting today, Thunderbird freezes during the "loading messages" process. I get a Windows hourglass and Windows tells me Thunderbird is "not responding."

Task Manager shows TB running but not taking up very many CPU cycles.

I suspect a damaged database, but what do I know?

Each of the tabs above is an email/message that was open the last time I ran TB.

I have no control over TB as it 'spins.'

I cannot find my TB version because TB is frozen. But it is fairly recent.

I need help.

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.