Below are the steps to fix QuickBooks Error Code 80040408:
- Reboot your computer and QuickBooks.
- Update your QuickBooks software to the newest version.
- Make sure your system is up to date, including all Windows updates.
- Run Disk Cleanup to delete temporary files that may be causing the error.
- Make sure your computer has the latest .NET framework installed.
- Make sure you have the latest Visual C++ Redistributable installed.
- Reinstall QuickBooks.