So basically it is like this. In my PC, I have an administrator user account and standard user account (my own account). I only use administrator account for installation purposes and system-wide maintenance. But for daily activity, including using UE4, I use standard user account. Normally, standard user account does not have write-access to any folder inside C:\Program Files. So when UE4 make some modification (like when compiling c++ code) in that folder, it crashes. The previous UE versions, never touches the C:\Program Files folder. But now, it does. That’s why I have this problem.