# Bug report: Garmin Connect FIT course import creates corrupt courses ("Invalid course" on device)
**First observed:** 2026-07-04 (evening, CEST)
**Re-confirmed:** 2026-07-10, on freshly updated Edge firmware, via the iOS Garmin Connect app
**Device:** Garmin Edge 1040 (Dutch UI), synced via Garmin Connect
**Where to file:** Garmin support / forums.garmin.com → Garmin Connect Web (also affects the iOS app import path)
## Summary
Importing ANY course FIT file via Garmin Connect — web (Training & Planning →
Courses → Import) **and** the iOS Garmin Connect app — produces a course object
that syncs to the Edge 1040 but fails to open with
**"Ongeldige koers. Wissen?"** ("Invalid course. Delete?").
This includes a course FIT file **exported by Garmin Connect itself** —
Garmin Connect cannot re-import its own export. The imported course renders
normally in the GC phone app (map, course points all visible); only the device
rejects it.
The same import path worked on 2026-05-24 (course imported then still opens
fine today). The regression window is therefore **late May – early July 2026**,
and it persists as of 2026-07-10.
## Evidence matrix
### Round 1 — 2026-07-04, GC web import, Edge 1040
| Test | Result |
|---|---|
| Send EXISTING course (created 2026-05-24 via FIT import, 173 course points) to device | 
opens fine |
| Import GC's own exported FIT of that same course (`COURSE_465831776.fit`) as new course → send | 
"Ongeldige koers" |
| Import GC's own export of another course (`Corvara-losrijden.fit`, exported 2026-06-30) → send | "Ongeldige koers" |
| Import third-party course FIT (validated clean by garmin-fit-sdk `check_integrity()`) → send | "Ongeldige koers" |
| Import the same course as **TCX** → send | opens (course points stripped, as usual) |
| Device reboot, deleting all courses on device + in GC, clean re-sync | no change |
| Old courses already on device | all open fine |
### Round 2 — 2026-07-10, iOS Garmin Connect app import, Edge 1040 on freshly updated firmware
Device software was updated to the latest available version immediately before
this round, ruling out stale-firmware causes.
| Test | Result |
|---|---|
| Import `GFNY_Grand_Ballon_Long.fit` — **Garmin Connect's own export** (file_id: manufacturer=garmin, garmin_product=connect) → sync → open | "Ongeldige koers" |
| Import third-party course FIT variant A (structure matching the 2026-05-24 working import: 12-byte header, cues appended) → sync → open | "Ongeldige koers" |
| Import third-party course FIT variant B (FIT-Cookbook-conformant: 14-byte header + CRC, timer events, interleaved course points, 50 cues) → sync → open | "Ongeldige koers" |
| Courses imported before the regression (May 2026) | still open fine |
Both third-party variants decode cleanly (fitparse; monotonic distance and
timestamps, course points in-bounds and interleaved, valid course-point types).
Their acceptance is irrelevant to the conclusion, however — **Garmin's own
export failing its own re-import** isolates the fault to the import pipeline
regardless of any third-party encoding choices.
## Conclusion
- Device is fine (old courses + newly *sent* existing course objects open; fresh firmware).
- Transport is fine (existing course objects deliver and open).
- TCX import path is fine (different parser).
- The file contents are irrelevant (Garmin's own export fails; spec-conformant
and legacy-shaped third-party files fail identically).
- **The FIT course import pipeline (web + iOS app) creates corrupt course
objects in the Garmin Connect database.** The GC app renders them fine
(lenient map view); the device's stricter course validator rejects the FIT
that GC's sync encoder regenerates from the corrupted object.
- Regression introduced between 2026-05-24 (last known-good import) and
2026-07-04; still present 2026-07-10.
## Impact
- Rider could not load a race course with nutrition/pacing course points onto
the Edge 1040 the night before Maratona dles Dolomites (2026-07-05).
- Recurred 2026-07-09/10 preparing GFNY Grand Ballon: course imports, shows
all course points in the GC app, and is rejected by the device.
- Affects every Edge user importing FIT courses (including files exported from
Garmin Connect itself); workarounds (TCX) strip course points.
## Reproduction (any account, ~5 minutes)
1. Export any existing, working course from Garmin Connect as FIT.
2. Re-import that same file as a new course (web or iOS app).
3. Send the new course to an Edge; open it on the device → "Invalid course. Delete?"
## Attachments to include
- `COURSE_465831776.fit` — GC's own export that GC's import corrupts (Desktop)
- `Corvara-losrijden.fit` — second GC-native example (Trash / re-export from GC)
- `GFNY_Grand_Ballon_Long.fit` — third GC-native example (Desktop), fails via iOS app import 2026-07-10
