Since I made a windows update, this error message appears when I start Fortnite:
FortniteClient-Win64-Shipping.exe - System Error
The execution of the code can't be continued because it was not found. Reinstalling the program may solve the problem.
(I have reinstalled the Epic Games Launcher or Fortnite 4 times.)
Simply uninstall the last Windows Update. If it is the 18.09 update, you will definitely need new hardware drivers before you install 18.09. But you can also without the 18:09 to uninstall search for new drivers.