Downgrade Firefox: Easy Step-by-Step Guide

Downgrading Firefox is surprisingly easy and can help if a recent update broke extensions, changed the interface, or slowed down your browsing. You can revert to an older version in about 10 minutes, but you must back up your profile first to avoid losing bookmarks, passwords, and settings. This guide walks you through the safest method using the official Mozilla archive, with clear steps for Windows, macOS, and Linux.

What You’ll Need

• A stable internet connection
• About 10 minutes of time
• Your Firefox profile backed up (explained in Step 1)
• Optional: a USB drive or cloud storage for the backup

Step-by-Step

1. Back up your Firefox profile. This is the most important step. Open Firefox, type about:profiles in the address bar, and press Enter. Find the profile marked “This is the profile in use� and click “Open Folder� (Windows) or “Show in Finder� (macOS). Close Firefox completely, then copy the entire profile folder to a safe location like your Desktop or a USB drive.
2. Find the exact version you want. Go to the official Mozilla archive at https://archive.mozilla.org/pub/firefox/releases/. This page lists every released version. Choose the version you want to downgrade to (e.g., 115.0 for the last version with legacy extensions).
3. Select your operating system and language. Inside the version folder, you’ll see subfolders like win64, mac, or linux-x86_64. Pick the one that matches your OS and architecture. Then choose your language folder (usually en-US for English).
4. Download the correct installer. In the language folder, you’ll find installer files. For Windows, download the .exe file (e.g., Firefox Setup 115.0.exe). For macOS, download the .dmg file. For Linux, download the .tar.bz2 archive.
5. Uninstall the current Firefox. On Windows, go to Control Panel > Programs and Features, select Mozilla Firefox, and click Uninstall. Choose the option to remove Firefox but keep your personal data (if prompted). On macOS, drag the Firefox app from the Applications folder to the Trash. On Linux, use your package manager to remove Firefox (e.g., sudo apt remove firefox).
6. Install the older version. Run the installer you downloaded. Follow the on-screen instructions. Choose the same installation directory as before if possible (default is fine). During installation, it may offer to import settings—skip that.
7. Restore your profile (if needed). After installation, launch Firefox once and close it. Then copy the profile folder you backed up in Step 1 back to its original location, replacing the new profile folder. On Windows, the default location is %APPDATA%\Mozilla\Firefox\Profiles\. On macOS, it’s ~/Library/Application Support/Firefox/Profiles/. On Linux, it’s ~/.mozilla/firefox/.
8. Disable automatic updates. Open Firefox, go to Settings > General > Firefox Updates, and select “Never check for updates.� This prevents Firefox from automatically upgrading to the newer version again. If you want to update later, you can change this back.

Common Mistakes

• Skipping the profile backup. Many users lose bookmarks and passwords because they didn’t back up. Always do this first.
• Downloading from third-party sites. Only use the official Mozilla archive to avoid malware or tampered installers.
• Choosing the wrong architecture. If you have a 64-bit Windows, download the win64 version. Installing a 32-bit version on a 64-bit system may work but can cause issues.
• Not disabling updates. If you forget, Firefox will update itself within hours, undoing your downgrade.
• Using a very old profile with a newer version later. If you upgrade again, your profile may be incompatible. Keep your backup until you’re sure.

Tips

• Choose a version that still gets security updates. Mozilla only supports the latest version and the Extended Support Release (ESR). If you downgrade to an older version, you’ll miss security patches. Consider using the current ESR version (e.g., 115.x) instead of an even older one.
• Test the downgrade on a spare profile first. If you’re unsure, create a new profile in about:profiles and launch the older version with that profile to see if your extensions work.
• Use a portable version for testing. You can download a portable Firefox from the archive (the .tar.bz2 for Linux, or use a portable launcher on Windows) to test without uninstalling your current version.
• Keep your backup until you’re satisfied. Don’t delete the profile backup until you’ve used the downgraded version for a few days.

Troubleshooting

• Firefox won’t start after downgrade. This usually means your profile is too new. Close Firefox, rename the profile folder (e.g., add .old), and let Firefox create a new one. Then copy your bookmarks and passwords from the backup manually if needed.
• Extensions are broken. Some extensions are not compatible with older versions. Check the extension’s website for a version that works, or use the “Add-ons� page to search for alternatives.
• Bookmarks are missing. If you didn’t back up, you can try to recover them from the places.sqlite file in the old profile. Use a tool like SQLite Browser to export bookmarks, but this is complex. Better to always back up.
• Firefox updates automatically despite your settings. Some enterprise policies or third-party software can override your update settings. Check about:config and set app.update.enabled to false.
• Downgrade fails on Linux. If you installed Firefox via Snap or Flatpak, you can’t simply replace it. Use the official Mozilla tarball instead, or use sudo apt install firefox-esr to get the ESR version.

Frequently Asked Questions

Will I lose my bookmarks and passwords if I downgrade?

Not if you back up your profile first. The profile contains all your data. If you skip the backup, you may lose everything, so always copy the profile folder.

Can I downgrade from Firefox 120 to Firefox 100?

Yes, but only if you back up your profile. Firefox may complain that the profile is too new, but you can force it by using the backup. However, security updates are missing, so it’s not recommended.

Is it safe to use an older version of Firefox?

No, it’s not safe for everyday browsing because it lacks security patches. Only use an older version temporarily or for specific testing. Consider using Firefox ESR instead, which is still supported.

How do I stop Firefox from updating after downgrade?

Go to Settings > General > Firefox Updates and select “Never check for updates.� You can also set app.update.enabled to false in about:config.

Can I downgrade on mobile (Android/iOS)?

No, the official archive only provides desktop versions. Mobile browsers are updated through app stores, and downgrading is not officially supported.

What is the difference between ESR and regular versions?

ESR (Extended Support Release) is a version that gets security updates but not new features for about a year. It’s ideal for users who want stability and compatibility with older extensions.

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