Summary
UEFN crashes on launch and never opens, on Fortnite/UEFN build ++Fortnite+Release-41.20 (Windows 11).
On launching UEFN from the Epic Games Launcher, a “Corrupt/missing files detected” dialog appears. Choosing either option then shows:
“Failed to open descriptor file ../../../FortniteGame/FortniteGame.uproject”
followed by a fatal error:
“ICU data directory was not discovered: ../../../FortniteGame/Content/Internationalization”
The editor never opens. Fortnite and Save the World both launch and play fine on their own, and both are installed on the same drive as UEFN. UEFN self-aborts on the descriptor/ICU check rather than crashing a module, which points to the UEVFS virtual file system failing to mount Fortnite content — likely a build-side regression, as other users report similar crashes on 41.20.
LoginId: c2516a414951ffd466dea3adecf4cd5c
Please select what you are reporting on:
Unreal Editor for Fortnite
What Type of Bug are you experiencing?
Other
Steps to Reproduce
- Install Fortnite and UEFN via the Epic Games Launcher (both on the same drive)
- Launch UEFN from the launcher’s “Launch” button
- A “Corrupt/missing files detected” dialog appears; choosing either option leads to the crash
Expected Result
UEFN opens normally and the editor loads.
Observed Result
UEFN crashes before the editor opens. First a dialog shows:
“Failed to open descriptor file ../../../FortniteGame/FortniteGame.uproject”
Then a fatal error:
“ICU data directory was not discovered: ../../../FortniteGame/Content/Internationalization”
LoginId: c2516a414951ffd466dea3adecf4cd5c
Already tried without success: verified both Fortnite and UEFN multiple times, clean reinstall of UEFN, cleared %localappdata% caches (FortniteGame, UnrealEditorFortnite) + reboot, ran launcher as administrator, confirmed user path has no special characters, toggled off Windows Sandbox/virtualization. Fortnite and Save the World both launch fine on their own. Version ++Fortnite+Release-41.20.
Event Viewer shows no application module fault — UEFN self-aborts on the descriptor/ICU check, which suggests the UEVFS virtual file system isn’t mounting Fortnite content. Appears to be a build-side regression; other users report similar issues on 41.20.
Platform(s)
Windows 11 (PC)
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Additional Notes
Event Viewer shows no Application Error module fault for UEFN — it self-aborts on the descriptor/ICU check rather than crashing a module. This points to the virtual file system (UEVFS) failing to mount Fortnite content, which looks like a build-side regression rather than a local configuration issue. At least one other user reported an identical crash on a recent build.