The document discusses error notifications that may be sent in response to an HSP 861 process. There are two types of error notifications: an email and an 824 application advice. The email provides a human-readable explanation of issues, while the 824 is an electronic document. Possible error messages include an invalid supplier code, part number, or mill coil that was not previously received. Corrective steps involve verifying information and contacting suppliers to resend documents.