QuickBooks Error 6000, 77 can also be seen, if the QuickBooks is not updated to the latest release. You can also come up with this error if the company file that you are trying to open is missing or damaged. If you are running an outdated QuickBooks version, then it is most probable to come up with this error. ND and . TLG files are part of your QuickBooks files. These are configuration files that allow QuickBooks to access a company file in a network or multi-user environment. If these files are corrupted or damaged, you will encounter these errors when you open your QuickBooks files.