Wrong GPS track after air raid — activity shows 86 km instead of 7 km

> When I try to edit the FIT file manually, Garmin FitCSVTool fails to rebuild the file after I change the distance.

I wouldn't use this tool (from the FIT SDK) for editing FIT files (although some recommend it) because it throws away a large amount of valid data in the conversion from FIT to CSV and back. The problem is that lots of data is rendered in the CSV as simply "unknown" (even though Garmin knows what it is [*]), without preserving the original numerical values. So when you convert CSV back to the FIT, you lose all of that data. Same issue if you use the FIT repair tool in the FIT SDK.

[*] I mean that Garmin obviously has code to write and read that "unknown" data in their devices and Connect, so at some level the company "knows" what the data is. But also, they don't publish that "unknown" data in the public FIT profile, so as far as the FIT2CSV tool is concerned, it's "unknown".

> Is there an official or recommended way to correct distance in a FIT file without breaking the file structure?

You could edit the distance in Garmin Connect itself (either the website or the app). It won't fix your GPS track, but at least your average pace should be corrected.

Just edit the activity in Connect and you will see an option to change the distance.

9384497 said:

Can Garmin Connect itself recalculate distance based on steps/HRM data if GPS is corrupted?

No, I don't think so.

Even though you'd rather use official Garmin stuff, here's some 3rd party apps/sites I can recommend for general use. 

Full Editing

- https://www.fitfilerepairtool.info/ is probably the most powerful and comprehensive tool, but it's not free and it only runs on Windows :/ (it's an MS Access app...) The user experience is not great and ofc the UI is super dated.

This *might* be able to fix your track / distance automatically, but I'm not sure. If you have Windows, you can use it in trial mode and at least see if it could fix the file (although you won't be able to save it)

Basic Editing:

- https://www.fitedit.io/ Free, modern app for Windows, Mac and Linux. Some parts of the user experience aren't great

Various Tools

- https://www.fitfiletools.com/#/top 

Viewing / Repairing

- https://www.fitfileviewer.com/ this is such a great tool if you want to *view* all the data in your FIT file, including stuff Garmin uses but hides from you (such as your activity and user VO2Max to 2 decimal places)