Thunderbird Community Forum

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

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

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?

Suddenly Thunderbird takes a long time to download even a few (10-20) emails from Gmail and then it freezes on an email and as I click on different emails only the original one shows on the bottom half of the screen, even if I change to a different folder/email account. Also it will not close when I hit the X in the upper right corner.

If I click on one of the other apps, such as Calendar it goes to calendar but when I go back to email it still shows that same frozen email.

I tried clicking on the three bars (hamburger) to find the Thunderbird version and nothing happens.

I have restarted the computer but that has not helped.

This is an add on to the previous portion that I wrote yesterday. Today nothing shows in the portion where I usually view the message after I've clicked on it. Also the options in the tool bar such as File, Edit, View etc. do not respond to a click after the first time I have attempted to look at a message.

I am considering uninstalling and reinstalling. If I do that will it find all my emails and folders etc. again? There are a few emails that I am quite desperate to access that I have put in folders.

I'd really appreciate any help I can get on this as some important work is being delayed until I can access those emails.

Thanks for any assistance!

I have a fairly old Thunderbird ESR Flatpak installed on my System76 Meerkat. Yesterday, it was working just fine. This morning, it refuses to launch, giving no error message from the desktop, and behaves as if something has been deleted.

I've been running TB for 10-12 years, generally with no problems. When I logged in on 5/13/26, I saw that Windows had run an overnight update:

    2026-05 Security Update (KB5089549) (26200.8457)

Thunderbird (version 147.0.2.0) was not running, although it had been when I slept the PC the previous night.

Now, when I try to start TB it gives me the crash report dialog. Selecting the Restart option just brings me back to the crash report.

In searching for possible causes, I see that this may be caused by a bad profile. So I open the profile folder with (run) %APPDATA%\Thunderbird\Profiles\ which in my case is:

  C:\Users\<user_name>\AppData\Roaming\Thunderbird\Profiles

This is an empty directory. But if I go up one level to \Thunderbird there is a profile.ini file which contains (actual user ID replaced by <user_ID>:

[Install8216C80C92C4E828] Default=E:\Thunderbird\Profiles

[Profile0] Name=<user_ID> IsRelative=0 Path=E:\Thunderbird\Profiles Default=1

[General] StartWithLastProfile=1 Version=2

"E:\Thunderbird\" is the correct location of my TB installation. In that directory is a profile.ini file that contains:

[General] StartWithLastProfile=1

[Profile0] Name=default IsRelative=1 Path=Profiles/<user_ID>.default

Directory "E:\Thunderbird\Profiles\<user_ID>.default" is present. But all of it's files are dated 2010 except Mail, dated 2016.

Directory "E:\Thunderbird\Profiles" contains the ImapMail and Mail sub directories totaling about 25GB data.

I don't know what the Thunderbird startup process is or if this all looks correct. Can someone give me a sanity check? If this looks normal, what else could be corrupted?

Thanks in advance.

I have accidentally opened up hundreds of mail I meant to delete. I cannot access my emails, Thunderbird keeps failing to respond. I have tried closing each tab but I cannot tell what is going on. Help please. I can't give the version as it doesn't respond to any instructions

After Windows installed an update in the middle of the night I can't open Thunderbird and I've tried uninstalling it and reinstalling with success.

It says: Thunderbird is already running, but is not responding. The old Thunderbird process must be closed to open a new window.

I've rebooted the PC, shut down the PC, ended the task and still nothing. It seem that Thunderbird didn't shut down correctly and the system still thinks that it's open and running. Anyone know how I can fix this issue?

Thanks,

Gregg