QuickBooks error 6143 occurs due to damaged or corrupted company files, incomplete installation, or improper network setup. This error can block access to your important files and cause QuickBooks to freeze. Fix QuickBooks error 6143 by running the QuickBooks File Doctor, removing spaces from file names, opening files locally, or renaming .ND and .TLG files. Follow these troubleshooting steps to quickly restore normal QuickBooks operations and protect your financial data.