This was driving me mad too! But sorted now thanks to this thread!
Hello there, this error just suddenly appeared and I found this thread. While the cmd prompt worked for me, i just got the error back after. Like after each successful launch (thanks to the cmd prompt), the error come back and i need to do the procedure again. Does anyone have a permanent solution ?
You can open the ■■■■■ from file explorer and delete UE4Game folder after a successful launch.