I have come across a case where an invoice generated from a PO delivery ended up having negative volume. It was not possible to open the invoice via VF03 , nor via VF02 to correct the incorrect volume value. I also tried to cancel the invoice via VF11 but all the methods gave a short dump with error DYNPRO_FIELD_CONVERSION. This implies that the screen processing action was terminated due to wrong values in some fields. To cross check the field which was in error, I checked VBRP table. The short dump also mentioned the same field VBRP-VOLUM. This was somehow negative.
Upon contacting SAP , they suggested a note which I would want to share in this forum.
Note : 367296 A billing document is corrupt: How it is repaired.
This note mentions usage of a report which is there in the correction instruction. This report would correct the error invoice and after which the consultant can cancel the same.
However, if due to rigid authorization processes in your project, if you cannot make arrangements for this report to be implemented in production at the earliest you could edit the VBRP entry in debug mode which is definitely not a good practice and you should refrain from doing so.