My Unreal Engine does not launch anymore

[valx]

My Unreal Engine 4.27.2 suddenly does not launch any more. A couple of days ago everything worked.
Now when I click launch I see the running process but do not see any UI at all. If I click launch again I see one more process, etc.

Already tried to run as an Administrator, complete reinstallation, rolled back last Windows update, disabled Antivirus - nothing helps.
Also, I cannot find any logs. Googled for log places but have nothing in these folders.
Is there any official documentation about where can I find logs?
My laptop is:
Windows 10, 16GB RAM
GPU Nvidia Quadro T1000 with 4GB.
Everything worked perfectly until today
Any help greatly appreciated.

[umishrak]

Try End Task of UE4E and restart.

[valx]

This was the first thing that I tried :D.
What is weird, it doesn’t generate any logs.
I probably need to enable logging somehow to understand what is going on.
Will try to leave this ghost process hanging for some time, maybe it will crash at the end.

[umishrak]

I am not sure, but check for this video if it helps.

What do you do when Unreal Editor crashes?

[valx]

Thank you for the informative video link. But in my case it doesn’t help, because I even not able to launch the empty editor by itself (to create a new project) and for some reason don’t have the “Saved” folder at all, so there are no any logs.

[DanM]

Could you try verifying the engine?

[valx]

Tried, even made complete re-installation. Didn’t help
I also asked for support in Unreal Engine forums: Unreal Engine Editor does not start any more - Installation & Setup - Unreal Engine Forums

[DanM]

How long have you waited for it to load?

[valx]

It is not loading at all. I see that there is some UEEditor process running but no UI appears at all. I don’t even have this Loading splash window - just nothing.
Already waiting for couple hours. And no logs. Even checked Windows Event log - nothing there too.

[DanM]

Have you tried uninstalling, restarting your PC, and then reinstalling?

[valx]

Already not sure… Will try later today.

[valx]

Found the reason of this issue - Windows Defender Firewall!
After connecting to different network in the office and launching UE4Editor, suddenly a Windows Firewall window appeared asking about access permission. After the grant, it started to work . When I returned home, it continued to work. But today it stopped to work again. So I disabled the Firewall and everything started to work again!
Looks like UE4 has some issues with Windows Firewall and it depends on some Internet requests before starting, and if such requests are blocked it just hangs without any errors and logs .