# Stale History

A Horizon server may be configured to reject historical requests when the history is known to be further out of date than the configured threshold.

In such cases, the `stale_history` error occurs and returns a [`503` error code](https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/503). To resolve this error (provided you are the Horizon instance’s operator), please ensure that the ingestion system is running correctly and importing new ledgers.

```bash
{
  "type": "https://expansion-testnet.bantu.network/horizon-errors/stale_history",
  "title": "Historical DB Is Too Stale",
  "status": 503,
  "detail": "This horizon instance is configured to reject client requests when it can determine that the history database is lagging too far behind the connected instance of stellar-core.  If you operate this server, please ensure that the ingestion system is properly running."
}
```


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