When I try to start UEFN, it stops at 90% and fails.

Here is the message.
“Log in failed: You are unable to log into your Epic Games account at this time. Please wait a moment and try again.
You must successfully log in to run UEFN. We are shutting down.”

The environment is Windows 11, 13th generation corei7, RTX 4060 (laptop).
I have tried restarting the PC, reinstalling UEFN, reinstalling UE, re-logging in Epic Games Launcher, etc., but all have failed.

I would appreciate it if you could give me a solution.

(Attachments are in Japanese. I’ll put it up just in case, but the meaning is as written above.)

Thank you for your report! We would like to look into this further, would you be able to submit a bug report using the form available here: Fortnite Creative

Thank you. I sent the bug report in that form!

I am still having trouble with it and would appreciate it if you could help me find a solution to this problem!

Sometimes it helps if Fortnite is already launched and when you launch the uefn session, select Connect to platform.

Sometimes it requires that you press Leave in the Fortnite window, so the uefn session can be started.

If the Fortnite window flickers a lot, I move it to another screen. Otherwise, Fortnite and UEFN will both crash and cause bluescreen.

Also, I avoid editing/saving a lot of assets at the same time. Because if the editor crashes, it will take a lot of time to launch everything again. And yes, I will be prompted to log in again. I use login with Google. I wonder if it is the problem and login can’t persist between launches.

I am able to play the Game mode most of the time, but sometimes I get crashes ( though there are no errors / runtime errors )

Specific errors can cause a crash, for example, trying to debug draw for a lot of objects. It is hard to determine the cause each time because logs do not record the specific error and only contain network errors.