Diễn đàn hỗ trợ Thunderbird

Additional details:

• Operating system: Windows (please specify your Windows version if known)
• The issue started on August 25, 2026.
• Thunderbird becomes unresponsive shortly after startup.
• A “System Integration” prompt appears before Thunderbird becomes unresponsive.
• I cannot click any buttons once Thunderbird becomes unresponsive.
• I tested both available profiles (“default” and “default-esr”) using the Profile Manager, but the same issue occurred with both profiles.
• I also started Thunderbird in Troubleshoot Mode with all add-ons disabled, but the issue still occurred.
• I can force-close Thunderbird through Windows when it becomes unresponsive.
• I have not deleted or modified any Thunderbird profile files because I want to avoid losing existing email data.
• The profile containing my email data appears to be “default-esr”.

I would appreciate any guidance on how to identify the cause of this issue and restore Thunderbird without losing my existing emails.

When trying to open Thunderbird it does nt with the message "Thunderbird Not Responding" I try to open in Troubleshoot mode but that does not wotk either. I have to start and re start the laptop and finally after many tries it finally opens. Frustrating

After reading my emails, I wanted to look at my address book. I clicked on ADDRESS BOOK and my book was not there. Now, I can't back up to a normal page. The only choice is to go to the taskbar and close that page. Then when I restart Thunderbird, I get the same useless page ! Now how do I get my emails ? PS I cannot get to the HELP page of Thunderbird in order to find the version number, so the number I posted below is probably wrong. But otherwise, I could not SUBMIT my plea for help. I'm really stuck !!

Yesterday and today I am opening Email and clicking on new message, as soon as I try to type in the email address that I am trying to send email to it disappears and I get error message and then I have to go back and open Email again.

My problem is that I can’t get into Thunderbird because each time I start it up I’m presented with a window that says "System Integration" (Not Responding)" and I have no way of making progress – all I can do is use Task Manager to exit TB.

The “system integration” window first appeared a few days ago and initially I was able to dismiss it by choosing the “Skip integration” option. Today was the first time it became unresponsive. No changes have been made to the system and TB should be up to date – though, not being able to open TB, I can’t check the version number (probably esr).

I have used TB for many years and have it installed on two PCs, both running on Windows 11. It’s working as normal on the other computer.

I’ve tried rebooting the computer, to no effect. I’ve also tried to open TB in troubleshooting mode but can’t get past the "System Integration" (Not Responding)" window.

It’s been a couple of months since I backed up so I’m really hoping there will be a solution that preserves all my emails, address book and calendar.

I’d be very grateful for any suggestions.

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!

how do I configure the account to minimize CPU resources when thunderbird starts up. Once I can get thuderbird to start OK, what are the next steps. It is likely this user has not powered this machine down more often than once every few months. And thanks, I don't anyone else who uses their computer like this.

can you add an option into the program that when it cant read the local emails from the disk for some reason, then it would ask for my permission to re-download everything and/or add an option to close or restart the program?

there is some really annoying bug when the Pc is in the process of using all of the available Ram (for some reason) and when i open TB at the same time, everything gets really slow, and instead of actually pausing to figure out what is wrong, the ******** ********** ****** just starts to throw in even more work to download all of the emails again for some reason, not even giving any explanation why it wants to do it in the 1st place....................... (while the screen even just blanks out, just because there isnt enough Ram avail to display all of this *********** *****........)

SHello Sometimes, on my iMac APPLE (OS Tahoe), THUNDERBIRD stops opening (message system: not responding ("ne répond pas" in French) There is no problem when launching the application, but issues arise later when returning to it after using other applications (Word, Excel, videos, etc.), THUNDERBIRD tourne en rond et ne s'ouvre plus. I have to close the application (via my Mac's system settings) and relaunch it for it to open normally again. I would appreciate any help if someone has experienced the same kind of issue. VAJP

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.

My computer unexpectedly shut down when the power went out. When I try to open Mozilla Thunderbird, it doesn´t respond. Messages appear on the tabs at the top and a dot flashes on one. When I press anything, the text turns gray and the program doesn´t respond. I´ve turned off my computer many times, and that doesn´t help. I´ve also deleted a locked file according to the instructions. The situation is the same in Safe Mode, and it doesn´t help. What should I do now? Thank you!

Every time I start Thunderbird it takes several minutes and sometimes doesn't start up. Once it does open up, emails do update new ones but if I go to account settings and select anything it hangs up. If I click on it, grays out and gets a message Thunderbird not responding. I have to open task manager to stop the program. Why aren't the emails on my email server get deleted/ moved updated when using Thunderbird? It seems like the only thing that happens only gets changed on the device I made changes to only. (computer, or phone or laptop)