Contact Record Status:
NOTE: Contact Upload file failure error messages may be viewed under Contacts > Uploads > . Clicking on the icon next to the desired upload file brings you to the Upload Results page where information about the upload is displayed. Next, select the Not loaded - critical error tab to see the contacts with the error.
This error occurs when a Delete upload is performed, but the External IDs for the contacts in the CSV upload file do not match the external IDs for the contacts in the organization. This can happen if the contacts were already deleted or the External IDs in the upload file are incorrect.
When using the Delete upload option, make sure the external IDs in your CSV upload file match those of contacts in your organization under the Contacts tab
In this example, the error occurred because the External ID for the contact in the file (ABC123) did not match any contacts in the organization.