3146015 Duplicate Server Events Detected

Meta is receiving identical Conversions API events multiple times without proper deduplication parameters. This inflates your reported conversions and skews optimization, causing Meta to over-optimize and potentially overspend.

What causes this error?

Meta is receiving identical Conversions API events multiple times without proper deduplication parameters. This inflates your reported conversions and skews optimization, causing Meta to over-optimize and potentially overspend.

How to fix it

1. Add event_id: Include a unique event_id parameter with every CAPI event. Use an order ID, transaction ID, or UUID.
2. Add fbp/fbc parameters: Pass the fbp (Facebook browser ID) and fbc (Facebook click ID) cookies from the user’s browser to your server for better matching.
3. Audit your server code: Check that your webhook or server-side code isn’t firing the CAPI endpoint multiple times per transaction (e.g., on page refresh or retry logic).