# Errors

Mav answers with a standard HTTP status and, in most cases, an `errors` list saying what went wrong.

- **400 Bad Request**: A required parameter is missing, or the body isn’t valid JSON. Example: `{"errors":["param is missing or the value is empty or invalid: phone"]}`
- **403 Forbidden**: The API key is missing or wrong, or your account isn’t on the current Mav app yet (`Account is not enabled for Next.`). Example: `{"errors":["API key is not authorized."]}`
- **404 Not Found**: The contact or conversion isn’t in your account. Lookups by ID answer with a `message` instead of an `errors` list. Example: `{"errors":["Contact not found."]}`
- **422 Unprocessable Content**: The conversion couldn’t be saved, like a negative `custom_value`. Example: `{"errors":["Custom value must be greater than or equal to 0"]}`