Hi andy_Bel
By chance, are you trying to edit an item invoice? If so do any of the items on the invoice have zero on hand quantity?
Assuming this is the case, take a backup of your file. Once you’ve got a backup, do an inventory adjustment to increase the on hand quantity by 0.01 and the relevant item cost for the quantity
This should allow you to now make the desired edits to the invoice. Once you’ve made the edits to the invoice, you can then either delete the inventory adjustment or record another one to reduce the items on hand quantity and value back to zero