This is caused by a either a corrupt QBDataServiceUserXX, disabled QBDataServiceUserXX, or if the password has been changed. QBDataServiceUserXX is a user that quickbooks creates to authenticate and start a service called QuickbooksDBXX. The service is responsible for managing access to the data in the company file. It can also cause multiuser issues if it is not running properly.
I got tired of running through the steps on the Intuit website so I whipped up this quick batch script. This will set a new password on the QBDataServiceUserXX account and restart the QuickBooksDBXX service.
@echo off set newpass=%random%%random%%random% echo Setting new password on QBDataServiceUser20... net user QBDataServiceUser20 %newpass% echo Setting password on service... sc config "QuickBooksDB20" obj= ".\QBDataServiceUser20" password= "%newpass%" echo Starting QuickBooksDB20 service... net start QuickBooksDB20