How to resolve Quickbooks POS invalid product number QuickBooks Error 176109 indicates Invalid product code which is caused due to the damaged files of point of sale.
Simple steps to fix : Invalid Product Number:
1. Open windows explorer (CTRL+E) and go to C:\ProgramData\Intuit\Entitlement Client\v8
2. Press CTRL+A from your keyboard in order to select all the files and then click on Delete
3. Click on Yes to confirm
4. Now open QuickBooks Point of Sale to re-register.