3740065 - Unable to add Purchase Order item via interface for Sales Order–linked item (category H)

• Unable to add a new item to an existing purchase order via interface using the Purchase Order OData V4 API.
• Material substitution from an external sales order is not reflected in the purchase order when the PO item is linked to a sales order (item category H).
• Attempts to update the existing PO item with a new material via interface are unsuccessful.
• No specific error messages or error codes are returned.

 SAP S/4HANA Cloud Public Edition

1. Create a purchase order with an item linked to a sales order (item category H).
2. Trigger material substitution in the external sales order.
3. Attempt to add a new item to the existing Purchase Order via the Purchase Order OData V4 API.
4. Attempt to update the existing PO item with the substituted material via the interface.
5. Observe that the new item is not added and the material update is not reflected, with no error message returned.

Purchase Order items linked to a Sales Order (item category h) do not permit material substitution on the existing item, so interface updates to replace the material fail.

1. Use the Purchase Order API service API_PURCHASEORDER_PROCESS_SRV to create a new line item in the existing Purchase Order.
2. While creating the new item, do not set account assignment category H, so the item remains independent of the Sales Order linkage.
3. If required, delete or mark the original sales-order-linked item for deletion instead of attempting material substitution.
4. Refer to the official API documentation:  for correct payload structure and endpoints for creating and updating Purchase Order items.
5. SAP Business Accelerator Hub

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