Enum describing possible header errors.

[Proto definition ![GitHub](https://developers.google.com/site-assets/logo-github.svg)](https://github.com/googleapis/googleapis/blob/master/google/ads/googleads/v25/errors/header_error.proto)

| Enums ||
|---|---|
| ## `INVALID_LINKED_CUSTOMER_ID` | The linked customer ID could not be validated. |
| ## `INVALID_LOGIN_CUSTOMER_ID` | The login customer ID could not be validated. |
| ## `UNKNOWN` | The received error code is not known in this version. |
| ## `UNSPECIFIED` | Enum unspecified. |