QuickBooks Multi-User Mode not working can disrupt collaborative accounting efforts, affecting productivity. This issue commonly arises due to network connectivity problems, firewall or antivirus settings blocking QuickBooks, or issues with the QuickBooks Database Server Manager. To resolve QuickBooks Multi-User Mode not working, start by verifying network connections and ensuring all computers can communicate properly. Check firewall and antivirus settings to ensure QuickBooks is allowed through. Update QuickBooks and the QuickBooks Database Server Manager to the latest versions. If problems persist, consider reinstalling QuickBooks Database Server Manager or consulting with QuickBooks support for advanced troubleshooting. Following these steps can help restore Multi-User Mode functionality, ensuring seamless collaboration in QuickBooks.