When many users are unable to access the company file at the same time, the message "QuickBooks Multi-User Mode Not Working" appears. Incorrect hosting configurations, firewall limitations, or database server problems are typical culprits. In order to fix this, you must make sure QuickBooks Database Server Manager is operating, check network configurations, and confirm that hosting is enabled on the server. Contact the QB support team at 1.855.738.2784 if you experience any problems.