Qbwin.log: LVL_ERROR--Returning NULL QBWinInstance Handle

QBWin.log displays the following error:

LVL_ERROR--Returning NULL QBWinInstance Handle

This message indicates that Verify Data was unable to complete.

1. Rebuild Data twice in a row
2. Verify data again
3. Now the QBWin.log will show new errors that will be useful in troubleshooting. 

If this solution does not resolve the issue, you can read discussions and post messages and questions relating to your issue on the Intuit QuickBooks Community site for free, or you can contact a technical support agent for additional guidance. Fees may apply.