Save again before you change invoice document & already released

What causes this issue?

The invoice document was already released for batch invoice
verification. If the invoice verification type is now set to 'no
invoice verification', you can only make further changes if the invoice
has not yet been checked automatically.

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?

To prevent the invoice being checked in the background, you must save
the document after the type is changed. This prevents the invoice being
checked in batch mode.
If you do not save the invoice document, and the system starts
processing in the background, the system blocks the invoice document,
and you can no longer process it online.

Error message extract from SAP system. Copyright SAP SE.