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Crash and Reboot (loop)

If your Garmin watch has been spontaneously restarting this issue can have several possible causes. Below is one fix that has worked in practice, worth trying before you go down the rabbit hole of factory resets or warranty claims.

The Symptom

The watch behaves normally most of the time, but under specific triggers it reboots unexpectedly:

  • Disconnecting the charging cable: You unplug the watch and instead of returning to the watch face, it restarts (potentially into a boot loop).
  • Starting an activity: You select a sport profile and hit the start button, and the watch reboots instead of beginning to record.

Too Many Stored .fit Files

Like most software bugs, this one can have multiple root causes, and Garmin's firmware is complex enough that no single explanation covers every case. But there's a pattern worth checking first: a large number of .fit files sitting on the watch.

The theory is straightforward: as the number of .fit files builds up, something in the watch's internal handling of that storage - indexing, reading, or writing during charge-cycle or activity-start events - gets bogged down or hits an edge case, triggering a crash and reboot.

Further troubleshooting showed that it's not only the activity files that count towards the limit, but all .fit files on the watch. In addition, starting with firmware version 26.09, the .fit files in the following folders are no longer cleaned up automatically if they haven't been synced with Garmin Connect:

Folder What it (most likely) stores
GARMIN/SkinTemp/ Overnight skin temperature readings used for Garmin's skin temperature feature.
GARMIN/Sleep/ Sleep tracking data recorded on the watch.
GARMIN/SlpDisr/ Unconfirmed. The name most likely abbreviates sleep disruption(s). A plausible candidate is the overnight breathing variations data, which the Epix measures with its pulse oximeter during sleep.

Normally each of these folders contains only six files. If the cleanup doesn't happen, they grow by one file per night and quietly push the total .fit count towards the point where the reboots start.

How to Fix It

  1. Connect the watch to your computer via USB and open the drive in a file browser. Make sure that the USB Mode of the watch is set to MTP.
  2. Check the number of .fit files in these folders:
    • GARMIN/ACTIVITY/ - your recorded activities
    • GARMIN/SkinTemp/
    • GARMIN/Sleep/
    • GARMIN/SlpDisr/
  3. Back up the .fit files locally by copying them to a folder on your computer before deleting anything.
  4. Delete the .fit files you've backed up:
    • In ACTIVITY, remove old activities. You don't need to remove everything - just clear out the bulk of the backlog.
    • In SkinTemp, Sleep and SlpDisr, keep the six most recent files and delete the older ones.
  5. Safely eject and disconnect the watch, then test the behavior that used to trigger the reboot (unplug the charger, start an activity).

If you're dealing with random reboots and haven't checked your on-device .fit file count in a while, it's a five-minute troubleshooting step that's worth trying before anything more drastic.

End a Boot Loop by Factory Reset

Data loss

A factory reset will erase data stored on the watch, so use this only as a last resort once you've backed up what you can.

If the reboots have escalated to the point where the watch is stuck in a continuous boot loop and won't respond normally, you can force a factory reset using a button combination. This method comes from androidauthority.com:

  1. Power off the watch by holding the Light button (top left) for up to thirty seconds.
  2. Press and hold the Back button (bottom right) and Start/Stop button (top right).
  3. Press the Light button briefly to power on the watch while holding the other buttons.
  4. On a beep, release the Start/Stop button.
  5. Once the second beep, release the Back button.