QuickBooks Error 176109 appears with the message – invalid product code or invalid product number. QuickBooks is powerful and highly efficient accounting software that allows users to easily perform complex accounting tasks. This accounting software boosts the productivity of the accounting department of small and medium-sized businesses (SMBs). However, while using QuickBooks, you may come across certain errors that impede your accounting work. One of the common errors that you may face is QuickBooks Error 176109. You may face this error while trying to open or register QB Desktop Point of Sale software. What causes QuickBooks Error 176109? There are various reasons that can lead to QuickBooks Point of Sale invalid product number error or QuickBooks Point of Sale invalid product code error. The main reasons are given below –