No, it supports Windows 10. Do you updated the latest version of Thunderbird? If Yes then It might be a driver compatibility issue. See if the same problem occurs in "windows safe mode with networking". That uses generic drivers. I'm suggesting this for troubleshooting, not as a workaround.

Do you by chance have Norton 360 installed? After lots of troubleshooting it seems that it was Norton that was causing Thunderbird to crash on my machine after updating to Windows 10. It was not a problem prior to the update.

Same issue here, and I have the current version. I don't have Norton installed. Everything was fine at first after a clean install of Windows 10, but after putting a filter on my IMAP that moves all inbound mail to the default folder instead of the inbox, it wants to freeze on startup.

In Safe Mode, everything is fine.

Hi soph,

You apparently marked this question as solved. I hope that indicates that you have fixed this problem, possibly by updating Thunderbird. Please reply again if you still have problems, or even just to confirm what worked for you.

I know some people solve the issue by using Thunderbirds safe mode but that is only intended as a troubleshooting step not a proper fix.

• Troubleshoot with Troubleshoot Mode Thunderbird
• Update Thunderbird to the latest version

I've learned to just wait it out. Eventually it works. I've done a clean install of Windows 10, so the mailboxes are imported.

I have this problem as well. I can see two factors causing it: 1. McAfee hogs 100% CPU if I leave the machine unattended. Once I am back it relinquishes this but it takes several minutes during which nothing work. 2. Once frozen, I can stop Thunderbird from Task Manager. It will restart OK but it is still frozen. The problem is that the initial kill does not work completely. After the frozen process has died TaskManager still shows Thunderbird as a process. If I kill this and restart then I get an unfrozen Thunderbird.

After upgrading to Windows 10, Thunderbird (38.2.0) was freezing periodically until I added it to the "approved programs" list in the Windows Firewall:

[http://windows.microsoft.com/en-us/wi.../communicate-through-windows-firewall#1TC=windows-7]

UPDATE: Thunderbird just froze up again, while "synchronizing" was displayed in the status bar. When it thawed, the status bar showed the message: "Error during sync. Click here to view the log." The issue appears to be related to the gContactSync add-on...

Another update: I've left gContactSync disabled for the last couple of months, and haven't experienced any freeze-ups. If I need to synchronize my contacts (fortunately not often), I temporarily enable the add-on, and disable it again when finished.

Just like most of those above, and very much like wildajo, I am having this problem. Freezes ('not responding') are frequent and sometimes several minutes in duration.

I am on a brand new fresh install of Windows 10, Home. Thunderbird 38.2.0. No norton; no mcafee. Sure, I have antivirus (panda free antivirus) and antimalware (MalwareBytes Antimalware premium).

I have already added Thunderbird to the windows firewall approved programs list. This has not helped avoid, reduce, or eliminate the freezes/'not responding' situations.

Like pencilartist I can wait it out, and have. But this is not a good solution. Several minutes of wait every time it happens, sometimes (at least, when I notice) dozens of times in a day. I work remotely so email is my lifeline.

I've used Thunderbird for some years now - at least a decade, probably more. So I am not new to this.

Current add-ons - .vcs support 0.6.4; configdate 0.75; lightning 4.0.2.1; lookout 1.2.13; smile fixer 1.4.1; Sticky Password Autofill Engine 8.0.4.34.

My latest thought is to try adding Thunderbird to the exclusion lists for malwarebytes and panda. OK - tried both. No change. Thunderbird still freezes and becomes unresponsive.

The original poster has marked this as solved, and that's fine with me. How about all you other folk out there - should I create a new question then, given that mine is _not_ resolved as of this writing?

Yishmeray

I even returned to using Thunderbird as POP3, and nothing has improved. Every new mail check after starting my PC takes a minimum of one minute to clear. I can even see all the new messages (today it was 17), but while Thunderbird is in a greyed out sort of mood, the only option is to wait until it's happy.

This is not the Thunderbird I have loved for so many years.

re : pencilartist said: In Safe Mode, everything is fine.

Thunderbird Safe mode does a bit more than just disable addon extensions, it also switches off hardware acceleration. So, if you have then restarted as normal and disabled addons but this did not fully resolve the issue, then try switching off hardware acceleration:

'Tools' > 'Options' > 'Advanced' > 'General' tab or 'Menu icon' > 'Options' > 'Options' > 'Advanced' > 'General' tab uncheck: 'Use hardware acceleration when available' click on OK

Most issues are related to another program interferring in the background. Windows, anti-virus, java, adobe etc updates. Running your computer in 'Safe Mode with networking' will tell you if another program is interfering. In these cases it is best to stop Anti-virus products from scanning incoming / outgoing emails. This is not the same as running scans on computer, in which case you should set quarantining to ask what to do rather than just delete else you might find a file with emails was 'fixed' by the Anti-Virus product and you could lose emails or set Thunderbird profile folders to be exempt from general scanning.

Set products that do updates to check for updates but to 'Ask' when to actually do the updating, so you can stop Thunderbird whist updating occurs.

Sometimes an addon can cause an issue - this is proved by checking in Thunderbird Safe Mode; if it works, then simply disabling the addon extension or updating the addon will fix. Trouble with addons should be reported to the author of the addon as they are responsible and not Thunderbird. Harware acceleration can also cause some issues, so switch it off as described above.

In IMAP mail accounts, you can choose to only download the last eg: 30 days to help with performance. 'Tools' > 'Account Settings' > 'Synchronisation & Storage' for the imap mail account. or right click on mail account name in folder Pane and select 'Settings' then select: 'Synchronisation & Storage' for the imap mail account. Select 'synchronise the most recent xx days' click on OK

Info on Thunderbird Safe mode:

• http://kb.mozillazine.org/Safe_Mode

General info on Performance issues:

• http://kb.mozillazine.org/Performance_-_Thunderbird

Information on anti-virus products:

• https://wiki.mozilla.org/Thunderbird:Testing:Antivirus_Related_Performance_Issues

Toad-Hall said

re : pencilartist said: In Safe Mode, everything is fine. Thunderbird Safe mode does a bit more than just disable addon extensions, it also switches off hardware acceleration. So, if you have then restarted as normal and disabled addons but this did not fully resolve the issue, then try switching off hardware acceleration: 'Tools' > 'Options' > 'Advanced' > 'General' tab or 'Menu icon' > 'Options' > 'Options' > 'Advanced' > 'General' tab uncheck: 'Use hardware acceleration when available' click on OK

---

Most issues are related to another program interferring in the background. Windows, anti-virus, java, adobe etc updates. Running your computer in 'Safe Mode with networking' will tell you if another program is interfering. In these cases it is best to stop Anti-virus products from scanning incoming / outgoing emails. This is not the same as running scans on computer, in which case you should set quarantining to ask what to do rather than just delete else you might find a file with emails was 'fixed' by the Anti-Virus product and you could lose emails or set Thunderbird profile folders to be exempt from general scanning.

Set products that do updates to check for updates but to 'Ask' when to actually do the updating, so you can stop Thunderbird whist updating occurs.

Sometimes an addon can cause an issue - this is proved by checking in Thunderbird Safe Mode; if it works, then simply disabling the addon extension or updating the addon will fix. Trouble with addons should be reported to the author of the addon as they are responsible and not Thunderbird. Harware acceleration can also cause some issues, so switch it off as described above.

In IMAP mail accounts, you can choose to only download the last eg: 30 days to help with performance. 'Tools' > 'Account Settings' > 'Synchronisation & Storage' for the imap mail account. or right click on mail account name in folder Pane and select 'Settings' then select: 'Synchronisation & Storage' for the imap mail account. Select 'synchronise the most recent xx days' click on OK

Info on Thunderbird Safe mode:

• http://kb.mozillazine.org/Safe_Mode

General info on Performance issues:

• http://kb.mozillazine.org/Performance_-_Thunderbird

Information on anti-virus products:

• https://wiki.mozilla.org/Thunderbird:Testing:Antivirus_Related_Performance_Issues

I am not using hardware acceleration. There is no AV present, other than Windows Defender. It doesn't scan emails. I have no add-ons in Thunderbird. Updates are already set to Ask. I'm not using IMAP, only POP3.

Nothing keeps Thunderbird from bogging down on the initial check, so I just ignore it until a few minutes have passed.

re :There is no AV present, other than Windows Defender. It doesn't scan emails. Windows Defender uses real-time protection to scan everything that you download or run on your PC. Windows Defender scans everything that enters your computer, whether through downloads, e-mail, networks, messaging programs, flash drives, or discs. So, I presume you have configured Windows defender to exclude your thunderbird profile folders from scans or switch off real time scanning.

If it only bogs down on initial check, then I suppose that's not too bad.

According to the answers on Microsoft, Windows Defender for Win10 does not scan emails or attachments before you open them.

http://answers.microsoft.com/en-us/protect/forum/protect_defender-protect_scanning/does-windows-10-defender-scan-emails/ad29b514-3edc-4c04-a522-c489f5b97b33

What bogs down Thunderbird, I may never understand, but Windows Defender not likely to be the culprit. If it was, Firefox should be exponentially much slower to open.

I have the same issue since installing Windows 10. Thunderbird freezes and freezes, and I didn't find any solution. I have installed the latest version of Thunderbird. I have deactivated firewall and virus scanner and windows defender. I did re-install Thunderbird. I have no add-ons. I have repaired the inbox folder. Nothing changes. Thunderbird is mostly not responding when I delete mails, but sometimes also when I reply to a mail. After several seconds waiting it works again. But only to freeze again with new activities.

I have the same problem except Thunderbird freezes and no response at all no matter how many times I close and restart. Very disappointed. I have to use Outlook all the time now and I much preferred Thunderbird when it worked. It worked after I installed Windows 10 and has only recently caused problems. I have 38.3 which I think is a recent update of Thunderbird. Maybe I should go back to the previous version

Windows Defender will scan anything you download or run as clearly indicated by MS website - from the horses mouth...

• http://windows.microsoft.com/en-us/windows-10/getstarted-protect-your-pc

I presume you understand that opening Thunderbird means you are selecting it to 'run'. When TB starts it checks for new mail and 'downloads'. When you open an attachment, it will use the appropriate program, so that will also get scanned.

Hence why I suggest you make sure it does not scan Thunderbird on startup. You should make Thunderbird program and Thunderbird profile folders an exception. If you do not want to let Windows Defender scans your specific files, folders, file types or process, you can put that on the Exclusion list. good info with images here: http://www.thewindowsclub.com/windows-defender-settings-windows-10

On startup loads of things get checked on the computer and this occurs in the background, so this is the most likely time for slowdown. Such things as updates to windows os, defender, scheduled scans that could not run at eg: 3AM, java, adobe etc. Most people have these processess occuring as auto.

There are some very useful hints in this link about performance. There can be various reasons.

• http://kb.mozillazine.org/Performance_-_Thunderbird

Some are due to your computer performing background checks, scans etc.. A Windows check for updates will always cause me a temporary slowdown. Hence why I do not allow it to start updating whilst I'm using Thunderbird. Some are due to how you maintain your Thunderbird. Hardware acceleration causes some issues for some people. ETC.

Do you keep your Inbox as an Inbox for incoming messages? Do you compact your Inbox and Junk regularly (most likely to have more activity - deleting emails, moving etc) ? Keeping the 'Inbox' low in numbers and compacting daily (if you delete quite a few emails ) will keep it in best condition.

If I uninstall and then reinstall Thunderbird, will I lose the contents of the folders I have?

I am unable to do any deletions as suggested as I am unable to use Thunderbird at all. It freezes immediately it is opened

FIXED!!! I have just run CCleaner (free download) and Thunderbird is now working without any problems (so far at least....)

marti1211 said

FIXED!!! I have just run CCleaner (free download) and Thunderbird is now working without any problems (so far at least....)

Be extremely cautious with CCleaner. It's powerful, and not always right.

I agree with pencilartist. CCLeaner can clear out stuff like temp folders, session information and 'remembered' passwords depending upon the settings you select and folders you make exempt.