QuickBooks Error 6210 occurs when there is a difficulty with QuickBooks' multi-user mode or the network role setup. This error tells us that QuickBooks was unable to verify the company file or network role setup. This can be due to your company file being damaged/corrupted, bad user permissions, or a bad hosting configuration. You can also receive this error when the system is unable to connect to the server, which can also fail to grant you access to your company data. With this error, you should first check your network connection. Verify that the computers have been configured correctly for multi-user access. You can also resolve error 6210 by running the QuickBooks File Doctor tool or verifying your company file for damage/corruption. Verify your system continually meets the network's requirements for QuickBooks.