Circle processes API transfer entities asynchronously after you make the initial create request. If a problem occurs while processing the request, Circle sets the `errorCode` property on the entity. This error can be retrieved either by polling the GET endpoint or from a notification.
## Transfer Error Codes
| Code | Description |
| transfer_failed | The transfer failed due to unknown reasons |
| transfer_denied | The transfer was denied by Circle Risk Service, see transfer `riskEvaluation` for more details |
| blockchain_error | There was an error processing the transfer on-chain |
| insufficient_funds | There was not enough funding to cover the transfer amount |