> ## Documentation Index
> Fetch the complete documentation index at: https://docs.lerian.studio/llms.txt
> Use this file to discover all available pages before exploring further.
# STA error list
> Lerian STA returns structured error responses. Look up each STA error code, what it means, and the HTTP status it carries.
**Error format**
Lerian STA returns errors as RFC 9457 problem details with the `application/problem+json` media type:
```json JSON theme={null}
{
"code": "STA-0016",
"detail": "The requested route does not exist on this service.",
"status": 404,
"title": "Not Found",
"type": "https://errors.lerian.studio/v1/STA-0016"
}
```
**Field definitions**
* **`type`** – A URI that identifies the error in the Lerian error catalog, built as `https://errors.lerian.studio/v1/`. A response with no `code` carries the RFC default `about:blank`.
* **`title`** – The HTTP status text (for example, `Not Found`).
* **`status`** – The HTTP status code.
* **`detail`** – A human-readable explanation of this occurrence. For `5xx` responses, STA replaces the detail with `internal error`. An internal cause stays out of the response body. Branch on `code` instead.
* **`code`** – A stable identifier for the error (`STA-NNNN`). Branch on this field. A request that fails request-schema validation carries no `code`, and `errors` names the fields at fault. Two errors can share a `title` and a status and still differ here. `STA-0005` and `STA-0016` both answer `404` with the title `Not Found`. The `code` tells you which one you got.
* **`errors`** – Optional list of individual error details, each with a `location`, a `message`, and a `value`.
## Request and routing errors
***
These errors apply to the request itself. They cover its syntax, its fields, its route, and the state of the service that received it.
| `code` | Description | Status |
| -------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------ |
| STA-0001 | Bad Request. The service could not read the request syntax. | 400 |
| STA-0002 | Internal Server Error. An unexpected failure. The `detail` reads `internal error`. | 500 |
| STA-0003 | Unauthorized. The resource requires authentication. | 401 |
| STA-0004 | Forbidden. The caller does not have permission for this resource. | 403 |
| STA-0005 | Not Found. The route exists, and the requested resource does not. | 404 |
| STA-0006 | Unprocessable Entity. The service read the request and cannot process it in its current form. | 422 |
| STA-0007 | Conflict. The request conflicts with the current state of the resource. | 409 |
| STA-0008 | Service Unavailable. A dependency the request needs is unavailable. Try again later. | 503 |
| STA-0009 | Too Many Requests. Too many requests arrived in a given period. | 429 |
| STA-0010 | Request Entity Too Large. The request payload is larger than the endpoint accepts. | 413 |
| STA-0011 | Bad Request. The fallback code for a client-side refusal without a dedicated entry. | 400 |
| STA-0012 | Missing Fields in Request. The request omits one or more required fields. | 400 |
| STA-0013 | Unknown Fields in Request. The request body carries one or more fields the endpoint does not accept. | 400 |
| STA-0014 | Invalid Request Fields. One or more supplied fields fail validation. | 400 |
| STA-0015 | Unmarshalling Error. A field carries the wrong JSON type, so the body cannot be decoded. The message names the field, the expected type, and the received type. | 400 |
| STA-0016 | Route Not Found. The request path does not match a mounted route. Correct the URL, because a retry gives the same result. | 404 |
| STA-0017 | Method Not Allowed. The path matches a mounted route, and the method does not. When the router refused the method, the response carries an `Allow` header that lists the methods the route accepts. | 405 |
## Credential and transfer errors
***
These errors apply to BACEN credentials, to inbound source configuration, and to the credential a transfer sends under.
| `code` | Description | Status |
| -------- | ------------------------------------------------------------------------------------------------------------------------------------------------------ | ------ |
| STA-0102 | Conflict. A rotation request targets a credential that is not active. | 409 |
| STA-0103 | Institution Code Conflict. A live credential already exists for the same institution code. | 409 |
| STA-0104 | Polling Budget Exceeded. The inbound source configuration would push the credential's inbound-discovery reserve past its queries-per-minute ceiling. | 422 |
| STA-0105 | Default Credential Not Resolvable. The request omits `credentialId`, and the tenant does not hold an eligible credential to resolve to. | 422 |
| STA-0106 | Default Credential Ambiguous. More than one eligible credential matches, so the service refuses instead of choosing one. Name the credential you want. | 422 |
| STA-0107 | Institution Credential Not Found. The supplied `institutionCode` does not match an eligible credential. | 422 |