After upgrading to Windows 11, Direct3D9 errors pop up frequently.

Here are the most effective short fixes:

1. Run DirectX End-User Runtime: Download and install the latest package from Microsoft. This often works better than Windows Update.
2. Update Other Drivers: Update your chipset drivers and BIOS/UEFI from your motherboard manufacturer's website. Outdated system drivers are a common cause.
3. Perform a Clean Boot: Identify if a background program is causing the conflict by starting up with only essential services running.
4. Use Windows' Built-in Troubleshooter: Run the "Hardware and Devices" troubleshooter in Settings.
5. System Restore: If the error started recently, roll back to a point before the issue began.