[40.20] UEFN exits with code 1 at 5s after driver swap, Fortnite launches fine

General Issues and Bug Reporting
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1

Summary

After the update, when I try to run the editor (Fornite itself works fine) it immediately pops up a dialogue for missing/corrupt files. goes to repair it but nothing is fixed and the next time I launch I get the same error.

Environment

  • Fortnite version: 40.20 (CL-52463280)
  • UEFN SKU: Fortnite_Studio
  • Windows 11 25H2 (Build 26200.8246)
  • GPU: RTX 3080, NVIDIA driver 32.0.15.9621 (595.xx branch)
  • CPU: Ryzen 5 5600X, 32GB RAM

Symptoms

  • UEFN process launches, exits with code 1 after ~5-8 seconds
  • No UnrealEditorFortnite.log written (dies before logger init)
  • No minidump written (dies before crash handler setup)
  • CrashReportClientEditor.exe spawns, reports ā€œApp/Death ExitCode:1ā€
  • Launcher then shows ā€œCorrupt or missing files detectedā€ dialog
  • Verify finds 678 files flagged (CEF3 locale paks, EAC binaries, Campaign movies)
    but Repair determines 0 chunks actually need downloading

Trigger

NVIDIA driver swap on 2026-04-16 at 07:47:43 (Windows event 20003)
while UEFN was running. UEFN GPU-crashed 7 seconds later at frame 73526 with
DXGI_ERROR_DEVICE_REMOVED (-2005270523) / Aftermath dump.
Has not successfully launched since.

What does NOT fix it

  • Full uninstall + reinstall of Fortnite/UEFN via Launcher
  • Reboot (multiple)
  • Clearing all caches (DXCache, D3DSCache, DerivedDataCache, Intermediate,
    Crashes, webcache, NVIDIA roaming state)
  • Deleting and regenerating Saved/ and Config/ folders
  • Nuking all EOS state (EOSOverlay, Epic Online Services, helpers)
  • Deleting stale Launcher manifest sidecars (19 orphans from prior install
    location + 2 orphan Pending sidecars)
  • Running Launcher as admin + creating fresh shortcut

Please select what you are reporting on:

Unreal Editor for Fortnite

What Type of Bug are you experiencing?

Stability

Steps to Reproduce

Run UEFN from launcher

Expected Result

UEFN launches

Observed Result

UEFN pops a ā€˜missing/corrupted fileā€™ windows dialogue box. prompts to do a file verification. It does said verification and finishes but the same thing happens on relaunch (have done this a dozen times or so)

Platform(s)

Windows 11

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Additional Notes

Fortnite client works fine, this is just UEFN
Might be related to NVIDIA driver update which I did this morning?
Everything worked fine yesterday

2

I did a full uninstall of Fortnite and reinstalled it and the Editor in a new directory after deleting all the old directories and that has cleared the issue.

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