Fixing Firefox Password Sync: Step-by-Step GuideIf Firefox Password Sync isn’t working reliably, it can be frustrating: saved logins don’t appear on another device, changes aren’t propagated, or sync just stalls. This step-by-step guide walks through diagnosis and fixes for the most common causes so you can get your passwords syncing again across desktop and mobile.
How Firefox Password Sync Works (brief)
Firefox uses a Sync account tied to your Firefox Account (email + password). When Sync is enabled, your saved logins, bookmarks, history, tabs, add-ons, and other data types are encrypted locally and sent to Mozilla’s servers. Only devices signed into the same Firefox Account with Sync enabled and the correct decryption key can read the synced data.
Before you start: quick checks
- Ensure you’re signed into the same Firefox Account on all devices.
- Confirm Sync is enabled for Logins and Passwords in Sync settings.
- Check that Firefox is up to date on each device.
- Verify internet connectivity and that no firewall/VPN is blocking Firefox.
If any of these are false, fix them first and see if the problem resolves.
1) Confirm Sync settings and account status
- Open Firefox.
- Click the account avatar (top-right) → Manage Account or Settings → Sync.
- Make sure you see your account email and Sync is enabled.
- Under “Sync” or “Manage Sync”, ensure Logins and Passwords is checked.
- If Sync shows “Paused” or “Needs verification,” follow the prompts to re-authenticate.
If the account shows errors (e.g., “Invalid credentials”) — sign out and sign back in (see step 3).
2) Update Firefox on all devices
Out-of-sync versions can cause issues.
- Desktop: Menu → Help → About Firefox → it will check and install updates.
- Mobile (iOS/Android): Update via App Store / Play Store.
After updating, restart Firefox and check Sync again.
3) Re-authenticate: sign out and sign back in (safe first step)
Signing out and back in often resolves token or session issues without losing data (data remains on Mozilla’s servers):
- Open Firefox → click avatar → Sign out.
- Restart Firefox.
- Sign back in with your Firefox Account credentials and enable Sync for Logins.
Note: If you have a Primary Password (older name) or a Firefox Lockwise primary password set, you may need to enter it for decryption.
4) Check saved logins locally
Make sure your local profile actually contains the passwords you expect.
- Desktop: Menu → Logins and Passwords (or about:logins).
- Mobile: Settings → Logins and Passwords (or similar).
If a password is missing locally on the primary device, Sync cannot push it out. Recover it from backups or another device where it still exists.
5) Resolve encryption/key issues
Firefox Sync uses an account key (derived from your password or a recovery key) to encrypt data. Problems here can cause devices to not decrypt incoming data.
Symptoms: devices show sync success but passwords are missing or appear as empty.
Fixes:
- If you used a Recovery Key when creating your account, ensure you used it on new devices. If you reset or changed your Firefox Account password without supplying the recovery key where required, previously synced data encrypted with the old key may be inaccessible.
- Try signing out and signing back in on all devices in quick succession so they share the same latest sync keys.
- If you changed your master password or account password and lost the recovery key, older encrypted data may be permanently unreadable — only newly saved logins will sync going forward.
6) Check for multiple profiles or conflicting profiles
If you use multiple Firefox profiles, make sure you’re checking the profile that contains your saved logins.
- Type about:profiles in the address bar.
- Confirm which profile is default and that it contains your logins (open about:logins while running that profile).
If another profile is active without your saved data, enable Sync in the profile that has the logins or export/import the saved logins.
7) Inspect Sync logs (advanced)
On desktop you can enable debug logging to see detailed Sync activity:
- Open about:config.
- Set toolkit.telemetry.debugSlowStartup to true (or use Firefox’s Sync logging guidance from Mozilla support).
- Alternatively, open Browser Console (Ctrl+Shift+J / Cmd+Shift+J) and watch for sync-related messages (search for “Weave” or “Sync”).
Look for authentication failures, sync errors, or decryption failures. These messages can point to token expiry, server errors, or corrupted local DBs.
8) Repair broken login storage (places to try)
Sometimes the local logins database (logins.json and key4.db) can get corrupted.
Option A — Refresh the logins database:
- Backup your profile folder (always do this first).
- Close Firefox.
- In your profile folder, locate logins.json and key4.db (and optionally logins-backup.json).
- Move logins.json and key4.db to a safe folder (don’t delete yet).
- Start Firefox — it will create fresh files.
- If you have a backup copy of logins.json (or another device still has the logins), you can try restoring them via Import (see step 10) or place the files back.
Option B — Use the login export/import feature:
- If one device has the correct passwords, export them (Menu → Logins and Passwords → … → Export Logins) to a CSV (protected with OS account access).
- Import the CSV into the device that lacks them (Menu → Logins and Passwords → … → Import from a File).
Note: Exporting to CSV is sensitive; keep the file secure and delete after import.
9) Disable interfering extensions or settings
Some privacy, security, or profile-managing extensions can interfere with Sync.
- Restart Firefox in Troubleshoot Mode (Help → Restart with Add-ons Disabled).
- If Sync works in Troubleshoot Mode, re-enable extensions one-by-one to find the culprit.
- Also check browser privacy settings (strict tracking protection or container extensions) that might block sync endpoints.
10) Mobile-specific checks
- Android: Ensure the Firefox Android app has background data and battery permission, and that Sync is enabled under Settings → Accounts or Settings → Sync.
- iOS: Ensure the app is allowed to use mobile data and background app refresh.
- If mobile still doesn’t sync, try clearing app cache (Android) or reinstalling the app after confirming passwords exist on another device.
11) When all else fails: reset Sync (last resort)
If Sync is irreparably confused between devices, you can reset the Sync data. This removes server copies, so be careful—ensure at least one device has the complete, up-to-date passwords.
Steps:
- Choose one device as the “source of truth” (it must have the full set of passwords).
- Sign into Firefox Accounts on that device, enable Sync.
- On other devices, sign out of Firefox Account.
- From the source device, go to Sync settings and choose to “Upload” or allow it to re-upload data (signing out/in may force a fresh upload).
- On the server side (Firefox Accounts settings via account management), you can manage or delete server data if necessary — use Mozilla account web interface.
- Sign back in on other devices; they should now download the server copy.
If uncertain, export passwords from the source device to a local CSV as a backup before resetting server data.
12) Protecting and troubleshooting in the future
- Keep Firefox updated on all devices.
- Periodically export a secure backup of logins (store encrypted).
- Enable 2‑step verification on your Firefox Account.
- Note your Recovery Key and store it in a secure password manager or vault.
- If using a primary/master password, remember it — losing it can render locally encrypted items inaccessible.
Quick checklist (summary)
- Signed into same Firefox Account?
- Sync enabled for Logins?
- Firefox updated on all devices
- Sign out/in to refresh tokens
- Verify local logins exist on source device
- Check encryption/recovery key issues
- Inspect profiles and login DB files
- Test in Troubleshoot Mode for extension conflicts
- Use export/import as backup and recovery
- Reset Sync only after backing up source data
If you want, tell me:
- which devices and OSes you’re using (Windows/macOS/Linux/Android/iOS),
- whether you see any specific error messages, and I’ll give device-specific commands or the exact sequence to recover your passwords.
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