This error usually occurs when a user tries to register or open POS. Call QuickBooks Point of sale support expert to get support for QuickBooks pos invalid product number. Need more help dial 1800-993-4190 QuickBooks Help Desk Number & get instant solution.. How to deal with QuickBooks Point Of Sale Invalid Product Number We have mention two solutions to this problem. QuickBooks pos invalid product number. This error can arrive due to Point of Sale Entitlement folder contains the damaged file. This error sometimes appears when upgrading Point of Sale to a newer version, or adding a client license to an existing Point of Sale network QuickBooks Point of Sale Invalid Product Number.