Backfilling a Sync

A backfill replays conversion data through an existing Sync for a specific time range. Use it to send historical conversions that the Sync would otherwise have missed.

When to use a backfill
Backfills are useful in situations like:

• Tracking gap. A period where the Sync was paused, the plugin was misconfigured, or the destination was disconnected.

• New destination. You’ve just connected a destination and want it to receive conversions from the days before it existed.

• Recovering from an outage. The destination platform had downtime, and you want to make sure no conversions were dropped.

If the Sync has been running normally and you simply want recent data, you don’t need a backfill — the next scheduled run will pick up new conversions automatically.

Which platforms support backfilling
Metrion stores your conversion data indefinitely, so the time window is only limited by what the destination platform accepts. Today, Google Ads is the only destination that supports re-uploading historical conversions, and it allows a maximum window of 7 days back from the current date.

Backfilling for Meta Ads, TikTok Ads, or Klaviyo is not currently possible. Those platforms don’t accept retroactive conversion uploads.

How to create a backfill
if you want to create a backfill, please let our team know and we will look into your options.

Fields in the dialog

• Choose syncs. The Sync(s) the backfill will run against. Conversions will only be sent to the destinations attached to those Syncs.

• Start time. The earliest moment in the time range to include. For Google Ads, the start time cannot be more than 7 days in the past.

• End time. The latest moment in the time range to include. Defaults to the current moment.

What happens after a backfill
Metrion queues the backfill and processes it independently of your regular Sync schedule. The conversions appear in the destination once the backfill finishes — depending on the volume, this can take a few minutes to a few hours.

To follow progress, open the Sync’s detail page and click the Logs tab. New entries will appear there as the backfill runs.

Tips and limitations

• 7-day cap on Google Ads. Enforced by Google Ads, not by Metrion. Anything older than 7 days will be rejected by the platform.

• Pick the smallest necessary window. Backfills include every conversion in the range — a tighter window finishes faster and avoids resending data already in the destination.

• Avoid duplicates. Google Ads deduplicates by transaction or order ID, but it’s safest not to overlap a backfill with a period the Sync already covered successfully.

• Check goals first. A backfill only sends the conversion goals currently configured on the Sync. Save any goal changes before backfilling.

• Consent rules still apply. Backfilled conversions respect the consent state captured at the time of the original event. Blocked events are not sent.

Troubleshooting

The backfill finished but I don’t see the conversions in Google Ads.
Open the Logs tab on the Sync. Green entries mean the run succeeded — Google Ads may simply take time to display the imported data. Orange or red entries point to records that were rejected; click into them for details.

I need to backfill more than 7 days.
That’s a Google Ads limitation. We retain the underlying data, but the platform won’t accept conversion uploads older than 7 days.

I want to backfill for Meta Ads or TikTok Ads.
Those destinations don’t currently support backfilling. The Backfill option is only available for destinations that accept retroactive uploads.

I want to backfill a Sync that doesn’t exist yet.
Create the Sync first (Tracking → Syncs → Add sync), then request a backfill.