QuickBooks Error 6123, 0- When QB user trying to restore QuickBooks Company Files from Hard disk or opens a Company file from the multi-network server.
Error display on your screen - "Error 6123,0 - We are sorry but QuickBooks can't open company file"

Causes:
Restoring company file from an external storage device
Network connection Issue
Damaged company file data
McAfee Antivirus installed in your system
Damaged Windows

Steps to Resolve QuickBooks Error 6123:
First, Remove special character from company name file
Download & Run QuickBooks file doctor
Rename .ND and .TLG file
Move Company file to a different location
Use the Auto Data Recovery Features
Disable the Antivirus Programs
Reinstall QuickBooks