3146006 Conversion API Event Mismatch

The events sent through the Conversions API (server-side) don't match or properly deduplicate with the events sent by your Facebook Pixel (browser-side). Meta is seeing double-counted or mismatched conversion data.

What causes this error?

The events sent through the Conversions API (server-side) don’t match or properly deduplicate with the events sent by your Facebook Pixel (browser-side). Meta is seeing double-counted or mismatched conversion data.

How to fix it

1. Implement deduplication: Every event sent via both the Pixel and CAPI must share the same event_id. This lets Meta deduplicate and count it only once.
2. Match event names: Ensure the event name (e.g., Purchase, Lead) is spelled identically in both the Pixel fire and the CAPI payload.
3. Use the Test Events tool: In Events Manager, use the Test Events tab to send test CAPI events and verify they’re being deduplicated correctly with Pixel events.