Delivery note is missing. You cannot continue

What causes this issue?

You assigned the invoice delivery note &V1&. This number does not exist
in the system. You are trying to determine items for the invoice by
going to the items or posting the document directly. This is not
possible.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Assign the invoice the purchasing document rather than the delivery
note, or change the invoice verification type and save without posting.

Error message extract from SAP system. Copyright SAP SE.