When attempting to cancel an order for a bib that has been deleted, DelOrder tries to cancel an order for which biblionumber="". However, the database shows NULL for aqorders.biblionumber when a bib has been deleted. Consequently, the cancellation fails. Adding to confusion, Koha doesn't give any indication of an error. The system gives a message that the order was cancelled but then, on returning to the basket, the order is still there.
*** This bug has been marked as a duplicate of bug 10869 ***