# API Response Codes

The Nelnet Payments API responses include two standard fields:

- **`responseCode`** : This field represents the result of the operation.
- **`responseMessage`** : This field contains description of the response code.


The table below lists known `responseCode` values. It includes:

- `responseCode`: The actual field returned by the API.
- `Category`: A classification of the response type (e.g., `APPROVED`, `INVALID_INPUT`, etc.).
- `Meaning`: A description of what the code typically means.


> ⚠️ **Only `responseCode` and `responseMessage` are returned in API responses.** The `Category` and `Meaning` columns are for documentation only and are not part of the response payload.


## ✅ Success Codes

| responseCode | Category | Meaning |
|  --- | --- | --- |
| A100 | APPROVED | Transaction was approved |
| A102 | PARTIAL_APPROVAL | Transaction approved for a partial amount |
| A103 | ACCEPTED | Transaction was accepted and will be processed at a later time |


## ❌ Error Codes

| responseCode | Category | Meaning |
|  --- | --- | --- |
| E400 | INVALID_INPUT | Input provided in the request is invalid |
| E401 | CONFIGURATION_ERROR | Failed due to merchant configuration issue on backend |
| E402 | DATA_NOT_FOUND | Input data not found on backend |
| E403 | DUPLICATE_TRANSACTION | Transaction is a duplicate |
| E404 | ENCRYPTION_ERROR | Encryption/decryption error encountered with provided value |
| E405 | FIELD_EMPTY | Field required a value but is empty |
| E406 | FIELD_MISSING | Expected fields are missing |
| E407 | FIELD_MISMATCH | Certain input fields don't match the values derived from backend |
| E408 | INVALID_AMOUNT | Input Amount is incorrect |
| E409 | INVALID_FORMAT | Format of the field value is incorrect |
| E410 | INVALID_LENGTH | Length of the field is incorrect |
| E411 | INVALID_ORIGINAL_TXN_ID | Input originalPaymentTransactionId field can't be found on backend |
| E412 | INVALID_STATE | Transaction is in an invalid state, so it can't succeed |
| E413 | INVALID_VALUE | Field value is incorrect |
| E414 | NOT_ELIGIBLE_FOR_REMITTANCE | Input account not relevant for remittance |
| E415 | TOKEN_DELETED | Provided token was deleted so it can't be used |
| E416 | TRANSACTION_TIMEOUT | Transaction timed out on backend |
| E417 | VALUE_NOT_ALLOWED | Input value is not allowed |
| E418 | VALUE_OUT_OF_RANGE | Input value is outside of the expected range |
| E419 | SYSTEM_DUPLICATE | A system-generated duplicate transaction was detected and blocked before execution |


### 🔁 Example Response


```json
{
  "responseCode": "E400",
  "responseMessage": ""
}
```