Document & cannot be cancelled

What causes this issue?

Document &V1& was posted with document type &V2&. Reversal document
type &V3& has been set for this document type. External number
assignment has been defined for this document type. This is not
allowed.

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?

Your system administrator must change the document type settings in
Customizing. The change depends on whether you are using conventional
Invoice Verification or Logistics Invoice Verification.
<ZH>Conventional Invoice Verification</>
In Conventional Invoice Verification, the reversal document type is
determined from the document type of the original document. You must
either set a different reversal document type for document type &V2&,
or change the number assignment for document type &V3&.
<ZH>Logistics Invoice Verification</>
In Logistics Invoice Verification, the reversal document type for
transaction MR8M is set in Customizing under "Document types, Invoice
Verification". You must either set a different document type for
transaction <LS>MR8M</> or change the number assignment for document
type &V3&.

Error message extract from SAP system. Copyright SAP SE.