There could be a number of reasons that you are facing QuickBooks error 6123 and as you are unable to access or restore the company file this indicates corruption in the QuickBooks Desktop application.
Follow the instructions listed below to quickly fix the issue.
Open Control Panel and click Add/Remove Programs option.
Now scroll down and select QuickBooks in the list.
Click Repair at the top and follow the instructions as they appear on the screen to repair QuickBooks Desktop application.
Once the application is repaired try to open or restore the company file and check if the error is now resolved.
If you can’t resolve QuickBooks error 6123 even after repairing QuickBooks Desktop application, then we suggest you get in touch with QuickBooks Desktop experts at 1-855-856-0042.