Within my testing system a tried the sale.order cancel process. I disabled automatic generation of outgoing goods for warehouse, because we do not need warehousing module at all (only purchase). This way, cancelling an order has become much easier - it is not required any more to first delete outgoing goods entry from warehouse.

So for now, I first cancelled the invoice. Having a look inside sale.order, a billing error was shown for this entry. Seems to be logical. Then I also wanted to cancel this sale.order. After having done this, the cancelled sale.order disappeared from list, but the state of all other sale.orders changed to 'undefinded'.

Can anyone explain me why? What do the other sale.orders have to do with the one I cancelled? I think, there should not be any of such side-effects. Maybe this is a bug?