> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://bcdtravel.ferndocs.com/invoice/guides/introduction/common-error-responses/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://bcdtravel.ferndocs.com/_mcp/server.

# Common error responses

We always respond to request failures with an HTTP status code and appropriate error details in the response body. This allows your application to programmatically resolve errors and provide inline error messaging within your application when appropriate.

## Error response format

```json
{
  "code": 400,
  "status": "error",
  "messages": [
    "Bad Request: The field `Field name` is invalid."
  ]
}
```

## Common error responses

### 400 Bad Request

```json
{
  "code": 400,
  "status": "error",
  "messages": [
    "Bad Request: The filter field is invalid."
  ]
}
```

```json
{
  "code": 400,
  "status": "error",
  "messages": [
    "Bad Request: Invalid Search Query."
  ]
}
```

### 401 Unauthorized

```json
{
  "code": 401,
  "status": "error",
  "messages": [
    "Access is unauthorized: An error occurred during authentication or authorization process."
  ]
}
```

### 403 Forbidden

```json
{
  "code": 403,
  "status": "error",
  "messages": [
    "Bad Request: API is disabled for the consumer."
  ]
}
```

### 500 Server Error

```json
{
  "code": 500,
  "status": "error",
  "messages": [
    "Server Error: Operation failed."
  ]
}
```

### 504 Gateway Timeout

```json
{
  "code": 504,
  "status": "error",
  "messages": [
    "Internal Server Error."
  ]
}
```

> Understand the error codes and responses returned by the Invoice API.