QuickBooks error 6190 is typically caused by some sort of company file corruption or damage that prevents QuickBooks from opening the file properly. Error 816 usually occurs during QuickBooks startup and indicates a problem loading the program components needed to run QuickBooks.

Potential sources https://toolhubquickbooks.com/quickbooks-error-6190-816/include damaged or missing system files, problems after a Windows or QuickBooks update, corrupted installation files, multi-user access conflicts, issues with antivirus or firewall software, or a damaged company file itself.

Identifying the specific underlying issue causing either error code requires troubleshooting steps like restoring backups, validating files, reinstalling QuickBooks, or updating system configurations. But the root causes of 6190 and 816 almost always stem from file, data, or software integrity issues.