This notification is only available for accounts using logicbroker dropship360. This error will occur for orders that do not have a supplier setup.
If you navigate to the Supplier Management page under dropship360 in Magento you will see the Supplier Code for your active suppliers (MagVendIDX)
If no supplier code matches, you may need to add a new Supplier/Warehouse through the portal or you may have to re-setup your products in magento to add them to the correct supplier. If you need help on that process here is an article to help on linking those products to your desired supplier.