Consumers see QuickBooks Error 6000 when they try to open a company file. It is characterised by a series of errors and is typically triggered by a range of circumstances. We can solve this by adjusting the firewall and antivirus software or restoring a backup. If still not resolved then try, accessing the business file in a different location and renaming the .ND & .TLG files. These are all simple methods to fix QuickBooks Error 6000.