Facebook Conversions API Diagnostic Guide
4 min
If you're experiencing issues with your Facebook Conversions API (CAPI) destination, this guide will walk you through common problems and how to resolve them. Each flow below addresses a specific issue with step-by-step troubleshooting instructions.
Events not appearing in events manager
Symptoms:
- Expected server events (like Purchase) are not visible in Meta Events Manager.
- You’ve recently configured CAPI but see no activity.
How to troubleshoot:
- Confirm the CAPI destination is created in Chord CDP and has an active connection with a back end source.
- Verify the Pixel ID and Access Token values for the destination correspond with the values listed in your Meta Business/Events Manager account
- Go to Meta’s Test Events tool and trigger a known action.
- Look for HTTP 200 responses and verify no errors like:
- 401 Unauthorized → Invalid token or app config
- 400 Bad Request → Missing or incomplete payload
- Retry with a minimal payload (just event_name, event_time, and user_data) to isolate the issue.
Duplicate events or overcounting
Symptoms:
- Conversion counts appear inflated in Meta Ads Manager.
- Same action appears twice under “Received Events.”
How to troubleshoot:
- Check whether Pixel and CAPI are both firing the same event.
- Confirm the event_id field is included in both and matches exactly.
- Visit Meta Events Manager → Diagnostics tab to see any deduplication warnings.
- Use the Test Events tool and look for a single deduplicated instance of the event.
Low match rate or inaccurate attribution
Symptoms:
- Meta Ads Manager reports poor attribution for key campaigns.
- Low conversion match rates despite CAPI being enabled.
How to troubleshoot:
- Confirm that user_data includes identifiers like:
- fbc / fbp
- Array of hashed external_ids including Anonymous ID and User ID
- Hashed email (em)
- Hashed Phone (ph)
- Hashed zip code (zp)
- Hashed country (ct)
- Hashed first name (fn)
- Hashed last name (ln)
- Turn on Advanced Matching in the Meta Pixel settings.
- Optionally, A/B test campaigns with vs. without CAPI enabled to evaluate impact.
Best practices recap
Recommendation | Why It Helps |
|---|---|
Use CAPI + Pixel | Covers blind spots, improves accuracy |
Use matching event_id | Prevents overcounting |
Include full user_data | Boosts attribution match rates |
Monitor Diagnostics tab | Flags misconfigurations |
Test frequently | Verifies end-to-end setup |