QuickBooks Error 6210 is the multi-user mode error which could be taking place for a number of reasons. It is essential to know the list of reasons so that eventually fixing the error is eased out.

1. QuickBooks Desktop and files related to it may not be completely installed.
2. QuickBooks Error 6210 is faced while installing QuickBooks on Windows.
3. Computer virus or malware has infected or deleted QuickBooks installation files.
4. Windows Firewall or third-party firewall is preventing QuickBooks from communicating with other workstations in the network.

Now, that you know the list of reasons for QuickBooks Error 6210, you can reach out to QB support team.