How conversions go missing
Server-side tracking is reliable, but it still depends on an unbroken chain. Break a link and events stop flowing until it’s repaired:
- A billing or account gap pauses event delivery for a creator — the subscriptions still happen, but nothing is sent.
- An expired Conversions API token silently drops server-side events until it’s reissued.
- A restricted domain gets its events refused by Meta until traffic is moved to a clean one.
In every case the conversions are real and they happened — they just never made it to Meta. Without backfill, that window is gone forever.
What backfill does
Because each visit is recorded with its match keys when the fan lands, the conversions from a gap can be reconstructed and resent once the cause is fixed.
- Identify the gapPin down the window where events stopped reaching Meta — usually flagged by attribution health when coverage drops.
- Reconstruct from stored dataMatch the confirmed conversions against the stored visit/tracking records so each event keeps its original match keys.
- Resend via CAPIDeliver the recovered events to Meta through the Conversions API — which accepts them even if the ad account was disabled during the gap.
Recovery only works within a short retention window — about the last several days of stored data. Catch the gap early and the events come back; leave it too long and the underlying data ages out, making the loss permanent. This is the strongest reason to run attribution health continuously.
Backfill is a safety net, not a substitute
The goal is always for events to fire in real time. Backfill exists for the days that go wrong — and paired with health monitoring, it turns an interruption into a footnote instead of a lost month.
Questions
When would I need to backfill events?
Any time conversions stopped reaching Meta for a stretch you can identify: a billing gap that paused delivery, an expired Conversions API token, a temporarily disabled account, or a domain that got restricted. Once the cause is fixed, backfill resends the conversions that happened during the gap so the record is whole again.
How far back can I recover?
Recovery depends on a short retention window on the stored visit/tracking data — roughly the last several days. Within that window, the conversions can be reconstructed with their match keys and resent. Beyond it, the underlying data has aged out and the events are unfortunately unrecoverable — which is why catching the gap early (via attribution health) matters so much.
Will Meta still attribute a backfilled event to the ad?
Yes, as long as it’s within Meta’s attribution window and the original match keys were stored. Backfill resends the real event with those keys, so it attributes the same way it would have in real time. Sent too late, it may arrive outside the attribution window and count for reporting but not optimization.
Does backfill work even if the ad account was disabled?
Delivery over the Conversions API is independent of the ad account’s serving status — events can still be accepted while an account is disabled. That’s what makes recovery possible even for gaps caused by account-level problems.
Don’t lose the conversions you earned
Recover events from an outage and keep your reporting — and your optimization — whole.