I am a regular QuickBooks user and have encountered multiple errors in the past time. Recently, I faced QuickBooks Error 6210, and I followed these steps that worked like magic-
Download and install the QuickBooks Tool Hub from the official website of Intuit.
Double-tap on the Tool Hub icon on your desktop.
Tap on the Network Issues tab.
Select the QuickBooks Database Server Manager from the menu.
When the program displays a prompt on your screen, click on the Start Scan button.
The QuickBooks Database Server Manager will run a scan on your device to identify and fix the issues.
Hit the Close button.
Open QuickBooks and your company file to see if the issue is resolved.
If you are looking for some more solutions, read here. You can also consult an expert on call at 1800-579-9430 to resolve the issue.