FIX: Thunderbird not responding or freezing. (Solved)

If Thunderbird is not responding, continue below to resolve the issue. Thunderbird is a popular open-source email client which is available for all platforms. But sometimes Thunderbird stops responding at all, or it freezes for 4-5 minutes before is usable again.

Thunderbird may not working, for the following reasons:

• The Antivirus program may prevent Thunderbird to connect to Internet.
• The Windows Search feature in Thunderbird messages may cause Thunderbird to freeze.
• A problematic Thunderbird setting or Add-on.
• Thunderbird indexing files (MSF files) maybe corrupted.

Because Thunderbird may not respond for a variety of reasons, in this tutorial we will show you all the available ways to solve the problem.

How to FIX: Thunderbird Not Responding or Freezes in Windows 10.

Method 1. Scan your computer for viruses.

Important: Many viruses or malicious programs can cause problems with Windows update. So before you continue to the troubleshooting steps below, use this Malware Scan and Removal Guide to check and remove viruses or/and malicious programs that may be running on your computer.

Method 2. Disable Windows Search in Thunderbird messages.

1. From Thunderbird’s menu, select Tools > Options.

2. In General settings, uncheck the option Allow Windows Search to search messages.

3. Restart Thunderbird.

Method 3. Add Thunderbird to Antivirus exceptions.

If you-re using a third-party antivirus on your machine, proceed and add the “thunderbird.exe” executable program to your Antivirus program’s exceptions.

For example, if you own the AVG Antivirus:

1. Go to Menu > Settings.
2. In General tab, click Exceptions > Add exception.
3. Click the Browse button and locate the thunderbird.exe file, (or copy & paste the below line) and then click Add Exception. *

• C:Program Files (x86)Mozilla Thunderbirdthunderbird.exe

* Note: If after adding the “thunderbird.exe file on your AV exceptions the problem still persists, add also to AV exceptions the folder where Thunderbird has been installed and the Thunderbird profile folder.

Method 4. Disable – Uninstall your Antivirus Programs.

Since the “not responding” issue in Thunderbird program, it is usually due to the Antivirus program, I suggest to disable or to completely uninstall your Antivirus program and to see if the problem still persists.

Method 5. Start Thunderbird in Safe Mode.

Thunderbird may freezing and not responding, if an installed extension causes problem or is damaged. To troubleshoot problems with Thunderbird’s Add-ons, proceed as follows.

1. Press and hold down the SHIFT key on your keyboard and open Thunderbird.

2. At the next window click Continue in Safe Mode.

3. If Thunderbird is not freezing in Safe Mode, then an installed add-on may cause the problem. At this case:

1. Close Thunderbird.
2. Press the SHIFT key and launch Thunderbird again.
3. At the next window, check Disable all add-ons and click Make Changes and Restart.

4. If Thunderbird is not responding again, continue to the next method.

Method 5. Reset Thunderbird Toolbars and controls.

1. Press and hold down the SHIFT key on your keyboard and open Thunderbird.

2. At the next window choose Reset Toolbars and controls and click Make Changes and Restart.

Method 6. Delete the Thunderbird’s Index (.msf) files.

In some cases Thunderbird is freezing, because the indexing files (aka MSF files), becomes corrupted. So, the final method to solve the “Thunderbird not responding” issue, is to delete the .MSF files. *

* IMPORTANT: Although MSF (Mail Summary Files) files can be safely deleted because they contain only the email headers and email status (read, unread, etc.), and not the actual email, it is recommended to backup the Thunderbird profile folder before deleting MSF files.

Step 1. Close Thunderbird.

Step 2. Enable the Hidden files view.

1. Navigate to Windows Control panel and open the Folder Options. (or the Files Explorer Options in Windows 10).

2. Select the View tab, and under the ‘Hidden files and folders’ section, check the Show hidden files, folders, and drives option and click OK.

Step 3. Delete the .MSF files

1. Navigate to the Thunderbird profile folder on your disk and open the Mail folder: *

2. Now explore the “Local Folders” folder* and delete all .msf files, or -better- move them to a (new) folder on your desktop.

3. When done, open Thunderbird and wait for Thunderbird to recreate the indexing files (MSF files).

That’s all folks! Please leave a comment in the comment section below or even better: like and share this blog post in the social networks to help spread the word about this solution.

If this article was useful for you, please consider supporting us by making a donation. Even $1 can a make a huge difference for us.