If you are getting this error, try running Fortnite with DirecX 11:
- Open the Epic Games Launcher.
- In the top-right corner, click on the Player Profile Icon (circle with first character of your Display Name).
- Select Settings.
- Scroll down and expand Fortnite.
- Check the box for Additional Command Line Arguments.
- Type: -d3d11
- Launch Fortnite.