4.4.1 Editor Not Launching from Launcher or cmd.exe

UE4 subscription was started tonight, installer downloaded, and installer completed on Windows 8.1. Launcher was executed, 4.4.1 was downloaded.

Steps to Replicate

#Launcher Method:

 - Open Launcher
 - Log In
 - Click Launch 4.4.1 Button
 - After a wait, button going grey, the button returns to yellow.

#Using CMD.EXE (using parameters in Launcher's shortcut):

 - cd C:\Program Files\Unreal Engine\
 - 4.4\Engine\Binaries\Win64\UE4Editor.exe
 - Error Message: "access denied"

Expected Result:

Editor starts.

Actual Result:

Editor does not start.

Additional Information:

Rebuild command in Launcher was attempted.

Expected log files are empty. Success log is “Just a record of success.”


Please assist. I’d hate to have thrown $19 away.

Please close this ticket. This issue has been self-resolved.

For future reference, owners of Avast! Anti-Virus need to add exclusions to all build tools, batch files, and executables found in their UE4 install directory.

A second solution is to disable Avast! Shields Control for the duration of their editing session.

I am glad you found the solution. Thanks for the update.