Unable to start UnrealEngine 4.27.2 stuck installing prerequisites

I am trying to follow an online course on UE5, in which UE4 asset pack is migrated. However, when I try to launch UE4 after installation it starts installing prerequisites, at some point EpicLauncher crashes (apparently), it closes the window and only the system tray icon is visible. In Task Manager it barely takes up any resources until I double-click the tray icon. Then it jumps to taking up about 15-20% of CPU and two sub-processes appear UE4 Prerequisites (x64) (32 bit).

And it stays like that for hours.

Could you please explain the behavior and/or how to fix it?

Thanks in advance.

Try to open a new empty project:

  1. Close the new empty project and delete the content folder.
  2. copy the Content folder into the new fresh project.
  3. Open the project.
    should work just fine. ( I hope )

well, as it appears UE5 also fails to install prerequisites.

The only difference in behavior is that after double-clicking the tray icon of EpicLauncher no longer takes 15-20% of the CPU, now it takes just 1%. But you can’t start UE at all.
And if I kill the UE4 Prerequisites tasks, I get the error: LS-0019-IS-PQR1

After PC restart and a lot of patience, prerequisites for UE5 got installed.

UE4 also succeeded.