Document type & not allowed here (Use F4 to see document types allowed)

What causes this issue?

According to the specifications for document type &V1&, you must assign
its document number externally. Therefore, you cannot use this document
type here.

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?

Use entry help to display the list of document types allowed. Choose an
appropriate document type.

Error message extract from SAP system. Copyright SAP SE.