Majorly QuickBooks error code 3371 occurs when your QuickBooks couldn't initialize the license properties and sometimes it appears on screen with a mistake code 1111 or error code 1. you'll eliminate QuickBooks error 3371 by deleting the ECML files. For that, you'll need to open the run dialogue box and enter the trail C:\program data\Intuit\entitlement client\v8 and hit enter. Once a replacement window opens, select the ECML file and delete it. Once done, you'll run QuickBooks again. Another fix is to update your windows OS to the newest version. the following pointers will assist you resolve QuickBooks error code 3371.