If you are using QuickBooks in a multi-user environment, any user who has the required file access rights can access the company file concurrently. QuickBooks Error 6073 And 99001 indicate that a different user is now opening or has already opened the same company file in single-user mode. When QuickBooks encounters [a]https%3A%2F%2Fdataservicesolutions.com%2Fblog%2Fsolved-quickbooks-error-6073-unable-to-open-the-company-file%2F[/a] you may see the message \QuickBooks is unable to open this company file. It may have been opened by another user\. To fix QuickBooks error 6073 use steps like <br>a) Setup QuickBooks on the Server in Multi-User Mode. <br>b) Multi-User Mode for the Company File <br>c) Permit complete access to the network folder <br> <br>You may face other QB issues with this one like Convert QuickBooks Desktop to Online. To resolve these errors get help from experts, you can connect with the QuickBooks Data Service Solutions support team by dialing +1-(855)-955-1942.