There are various types of errors that QuickBooks encounters while installing and updating QuickBooks Desktop application. One of such errors is QuickBooks Error 1603 that mostly evolves while installing QuickBooks on Windows for the first time and is caused by damaged or corrupt QB installer file. Users notice QuickBooks update error message “Error 1603. The update installer has encountered an internal error.” and are suggested to repair QuickBooks to fix the error. This article is intended to focus on the faults that evoke 1603 error in QuickBooks along with the error repair method.