First: charge the watch and switch it on
Charge the watch and switch it on before anything else. Garmin forum users report that after charging, their watch offered to recover the activity and save it. If yours does, save it: it then syncs like any activity.
Do not reset the watch to its factory settings to “fix” it: a reset can delete the unsaved activity.
What happened inside the file
During an activity, the watch writes the points one by one into a .fit file. At the end, when you save, it writes the summary (the last lap, the session and the activity), sets the final size in the header and adds a checksum.
When the battery dies, none of this is written. The file stops in the middle, its header still announces an unfinished size, the checksum is missing and the summary does not exist. Some apps refuse the file; others show it without distance or duration.
Real files from forum threads show another pattern: when the watch restarts during the activity, it can write an empty lap. Garmin Connect refused such a file until the empty lap was removed.
Recover the activity, step by step
Copy the file from the watch
Connect the watch to a computer with its USB cable and copy the .fit file of that day from the GARMIN/Activity folder. If it is not there, look in GARMIN/TempFIT: some watches keep data there.
Open it in FIT Rescue
The diagnosis shows the cut-off end, the size, the checksum and the missing summary.
Rebuild the summary
The repair “Rebuild the missing summary” writes the final timer stop, the last lap, the session and the activity from the recorded points: time, distance, speed, heart rate, cadence, power and elevation.
Download and import
Download the repaired file and import it in Garmin Connect (Import Data on the web) or Strava.
What FIT Rescue repairs
- The cut-off end and the unfinished header
- The missing checksum
- The missing summary: last lap, session and activity rebuilt from the points
- An empty lap written when the watch restarted
What it cannot do
- The part of the activity after the watch stopped: it was never recorded
- Calories and training effect, which the watch calculates at the end: they stay empty
- A file the watch never created or that was deleted
Repair the unfinished file
Drop the .fit file the watch left: the summary is rebuilt from the recorded points.
Questions
My watch died mid-run. Is the activity lost?
Usually not: the points recorded before it stopped are in a .fit file on the watch. Charge it first, and if it offers to save the activity, save it. Otherwise, copy the file and repair it.
Where is the file of an unsaved activity?
On most Garmin watches, activity files are in the GARMIN/Activity folder, which you reach with the USB cable. Files are named after the date and time of the activity.
Will the repaired activity have its distance and time?
Yes: they are rebuilt from the recorded points. Calories and training effect cannot be rebuilt.
Will the activity count in my training load?
That depends on Garmin Connect and the watch, not on the file. A forum user reports that an activity recovered after a flat battery did not appear in the watch’s load history.
Sources
Related guides
FIT Rescue tools
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