Sync Failed
Fitbit Smart Watch
Severity: MinorWhat Does This Error Mean?
Fitbit shows a red sync icon, error toast, or 'Couldn't sync' message when the app cannot transfer data from the device.
The device keeps recording — data is not lost — but you cannot see it until sync completes.
Cause is usually Bluetooth on the phone, the device being out of range, or the Fitbit app needing a refresh.
Most cases clear in under five minutes.
Affected Models
- Fitbit Sense and Sense 2
- Fitbit Versa, Versa 2, 3, and 4
- Fitbit Charge 5 and 6
- Fitbit Inspire 2 and 3
- Fitbit Luxe
Common Causes
- Bluetooth disabled on the phone
- Fitbit out of range (over 30 feet from phone)
- Fitbit app permissions revoked after OS update
- Battery Saver mode throttling background sync
- Fitbit app outdated
- Google account migration left old auth tokens
How to Fix It
-
Force-quit and reopen Fitbit app.
Close Fitbit completely from the recent apps view.
Reopen.
Pull down on the home screen to trigger manual sync.
Most stuck syncs clear here on the second or third try. -
Check Bluetooth.
Phone Settings → Bluetooth → on.
Wear the Fitbit on your wrist, or hold it next to the phone.
Bluetooth Low Energy is range-sensitive — across-the-house sync is unreliable. -
Verify app permissions.
iOS: Settings → Fitbit → confirm Bluetooth and Background App Refresh on.
Android: Settings → Apps → Fitbit → Permissions, allow Nearby Devices, Location, and Physical Activity.
Missing permissions silently break sync. -
Disable Battery Saver.
Both iOS Low Power Mode and Android Battery Saver throttle background tasks.
Disable while troubleshooting.
You can re-enable once sync is stable. -
Update the Fitbit app.
App Store / Play Store → Fitbit → Update.
Sync handling has improved across versions.
Restart the app after updating. -
Restart Bluetooth.
Toggle Bluetooth off, wait 10 seconds, toggle on.
This forces a fresh Bluetooth state without unpairing.
Resolves stuck pairing states. -
Restart the Fitbit.
Hold the side button (or specific combo for your model — see manual) until the Fitbit logo appears.
Restart clears any local state that may be blocking sync. -
Sign out and back in.
Fitbit app → Profile → Sign Out.
Sign back in with Google account (or Fitbit account on legacy migrations).
Refreshes auth tokens.
Fixes sync issues that survive restarts.
Frequently Asked Questions
Will I lose data if sync stays broken for a week?
The Fitbit holds about a week of detailed data on board.
Beyond that, the oldest data starts rolling off as new data is recorded.
Resolve sync within a few days for guaranteed data preservation.