QuickBooks Error 6144 arises when you attempt to access a company file, which some other application is already using. Give a look at these troubleshooting steps mentioned below to resolve the problem and start using QuickBooks:
 You need to repair all the Windows Registry entries associated with QuickBooks
 Update the PC drivers before using QuickBooks
 Reinstall QuickBooks in order to get the latest version
 Use an alternate computer to access the company file
 Make sure that the antivirus is compatible with the QuickBooks software
For more details about how to get rid of the issue, you can call the quickbooks customer care number and have a word with a trained expert.

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