Fortnite crashes when launching a UEFN session with Mobile Preview enabled

Summary

When I launch a session in UEFN using the Mobile Preview option, Fortnite crashes immediately when the session starts.

This happens consistently for me, and I have tried multiple device profiles and mobile preview configurations, but the crash occurs regardless of which profile I select.

I discovered that the only way I can currently fix the issue is by deleting the GameUserSettings.ini file located at:

%LOCALAPPDATA%\FortniteGame\Saved\Config\WindowsClient\GameUserSettings.ini

After deleting this file, Mobile Preview starts working again. However, doing this resets all of my Fortnite settings, including my video, resolution, display, and other game settings.

The problem can then return after changing certain settings again. In my case, changing the resolution/display mode to Windowed Fullscreen, along with other video settings, eventually causes Mobile Preview to start crashing again.

I am not sure which specific setting is causing the issue, but it appears that something being saved to GameUserSettings.ini is causing Fortnite to crash when UEFN attempts to launch a Mobile Preview session.

Please select what you are reporting on:

Creative

What Type of Bug are you experiencing?

Assets

Steps to Reproduce

  1. Start a session using Launch Session.
  2. Select the Mobile Preview option.
  3. Select any available mobile device profile/aspect ratio.
  4. Launch the session.
  5. Fortnite crashes immediately while attempting to launch the Mobile Preview session.

Expected Result

The Fortnite client should successfully launch the Mobile Preview session when selecting a mobile device profile in UEFN.

Observed Result

Fortnite crashes immediately when UEFN attempts to launch a Mobile Preview session.

Platform(s)

Windows PC

FORT-1152929 has been created and its status is ‘Unconfirmed’. This is now in a queue to be reproduced and confirmed.