Running the Quick Fix my Program tool from QuickBooks Tool Hub can help resolve the error:
Close QuickBooks.
Download the latest version of QuickBooks Tool Hub.
Move to downloads.
Open the QuickBooksToolHub.exe file.
Start installing the tool hub by following the step-wise instructions.
Agree to the terms and conditions.
Once the install completes, the QuickBooks Tool Hub icon will appear on the desktop.
Open the QuickBooks Tool Hub.
Select Program Problems.
Click Quick Fix my Program.
Start QuickBooks and try to open the company file.
Connect with the certified QuickBooks expert’s team by dialing our helpline number (1800-579-9430) if you need help to resolve QuickBooks error 6123.