If you are changing the serial flag for an item from N to S the system will allow the change unless the item is a nonstock item (you may not serialize nonstock items) or unless any of the following inventory transaction types have been processed for the Item (in any of the inventory locations in which the item exists).
OI, DI, DS, OS, VS, VP – If any Invoices, Shippers or Vendor Shipments (direct or thru pending) have been processed for the item, the system will block you from making the change to the serial flag as the invoices for the item do not have serial numbers associated with them. This logic also covers transactions that are processed from the pending file - if the item has been invoiced into pending with an OS or DS transaction, you are blocked from changing the flag – this covers Pending Write-offs PA) Returns to Vendors (RD), Returns to Inventory(RI), and Pending Invoices(PI). Return Authorization activity is also handled by this restriction (an RA credit or replace will generate OI transactions when the items are returned to stock or the replacement order is invoiced).
VS,VP – If any transactions that represent both a receipt and a sale or shipment to pending (such as a vendor shipment or a vendor shipment to pending) has been processed for the item, the system will block you from making the change to the serial flag. In this case, the sales track only item should have serial records for the vendor shipment transactions and they will not be in the system.
SF,CC,WI,WO – The Sales Track Only Serial option is not supported in the Shop Floor system as this option does not allow any verification of the serial numbers being recorded in the shop order. If you have already processed shop order transactions for the item, the system will block you from changing the serial flag from N to S. All serialized items used in the Shop Order System must have the Serial flag set to Y.