How to downgrade ThunderBird Supernova 115 to Regular Thunderbird 102 Email

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How to Downgrade Thunderbird

Thunderbird recently pushed an Automatic Update which introduced a lot of bugs and broke a lot of commonly used Features. If you were one of these unfortunate people, there is hope to return to the Thunderbird you know and love. Use the below steps to Revert to the previous version and prevent future automatic updates.

Downgrade Thunderbird Supernova 115 to Version 102


Option 1: You can delete compatibility.ini from Thunderbird's profile folder and then reinstall the older version. This should revert to the older version.

  1. Open Thunderbird.
  2. Open the Troubleshooting page via Menu ☰ -> Help -> Troubleshooting information
  3. Click Profile Folder and select Open folder.
  4. Close Thunderbird
  5. Delete compatibility.ini file from the folder you opened.
  6. Download Thunderbird 102.15 installer or Portable Version.
  7. Use the installer to re-install the older version (overwrite the newer one)
  8. Relaunch Thunderbird.

Version 102 should be restored.

Option 2: If option 1 does not work, try the following to launch Thunderbird with the "--allow-downgrade" switch:

  1. Close Thunderbird.
  2. Right-click your Thunderbird Desktop shortcut.
  3. At the end of the Target field add --allow-downgrade after the file path.
  4. Relaunch Thunderbird.

Version 102 should be restored.

Prevent Future Updates

You can prevent Thunderbird from automatically updating by placing a JSON file in a folder called Distribution. We have a link to this file or steps to create it yourself.

  1. Click Here to download the premade JSON file and save it to your PC.
  2. Open Thunderbird's Program Folder (e.g. C:\Program Files (x86)\Thunderbird or C:\Program Files\Thunderbird for 64bit).
  3. Create a new folder called distribution
  4. Place the "policies.json" file in this folder.

Create the File Yourself:

  1. Create a new text file Add the below quoted text to the file.
  2. Save the file and name it "policies.json".
  3. Open Thunderbird's Program Folder (e.g. C:\Program Files (x86)\Thunderbird or C:\Program Files\Thunderbird for 64bit).
  4. Create a new folder called "distribution".
  5. Place the "policies.json" file in this new folder.


"policies": {
"DisableAppUpdate": true,
"DisableFeedbackCommands": true,
"DisableSystemAddonUpdate": true,
"ExtensionUpdate": false


My Experience with Thunderbird 115 Supernova

My experience with Thunderbird Supernova was very poor. On a busy Monday morning, I see a bright splash screen, and I ignore it I get about 200 emails a day and respond to about 30 of them, primarily in my first hour of work and primarily using a little macro tool. Suddenly, without asking my permission, right in my face was a tiny bold font of barely readable text called my inbox! I looked in horror at how this would mess up my busy Monday.

I tried to fix the mailbox font using Settings Font settings. But this fixes the view email font and not the font for the titles of the 200 emails that was facing me on my inbox. I worked with it for 10 minutes and then halted my entire morning routine to find how to update the mailbox font and found a fix for that. That will be posted on another page for those who still use Supernova.

After replying to an email, I file the email in my offline folders. This is a normal productivity technique to remove mail after processing and store it in a safe spot for later reference. Having saved every business email since 1996, my offline folders are extensive. I am so familiar with the keystrokes I barely think of it. Email about this topic is filed M-M-M-I-A and the next email would be M-M-M-I-S-U. But with Supernova, my keystrokes did not work. I had to use my mouse, which was very slow. I later learned if I closed Supernova and restarted it, my keystrokes would work for 5 or 10 minutes before they stopped working.

I can live with the font update - because I found a workaround. I can live with the bold text. But I can't file 30 emails a day without my hotkeys. So I looked and found how to roll back.

Shame on Thunderbird for not giving the option to update with a warning and clear documentation on what it would do. Shame on them for not making a setting to undo the update quickly. Shame on them for mixing a functionality update with a UI update. And finally - obviously - shame on them for not testing thoroughly enough to find the keystroke handling issue before release.