When receiving a purchase order, you may see a warning banner:
Some variants no longer exist. The following product variants have been deleted from Shopify and cannot be received.
This means one or more product variants that were originally added to the purchase order have since been deleted from your Shopify store.
Deleted variants cannot be received. The received quantity for these line items will remain unchanged.
Review the listed products — the warning banner lists exactly which variants no longer exist in Shopify.