Summary
UEFN won’t launch on Release 43.00. It shows “Corrupt/missing files detected”, then “Failed to open descriptor file ../../../FortniteGame/FortniteGame.uproject”, and exits (exit code 3) without writing an editor log. FortniteGame.uproject and FortniteGame\Content\Internationalization are never downloaded, because the Epic Games Launcher drops UEFN’s install components every time. This looks like FORT-1152398 again: it was reported fixed by the 42.40 patch, but it’s happening on 43.00. Verifying, updating, and reinstalling UEFN don’t fix it. Fortnite itself launches normally.
Please select what you are reporting on:
Unreal Editor for Fortnite
What Type of Bug are you experiencing?
Stability
Steps to Reproduce
- Have Fortnite installed and up to date (++Fortnite+Release-43.00-CL-59596594-Windows).
- In the Epic Games Launcher, uninstall Unreal Editor for Fortnite, then install it again.
- While it installs, open %LOCALAPPDATA%\EpicGamesLauncher\Saved\Logs\EpicGamesLauncher.log and look at the LogEoshPatcher lines for Fortnite_Studio.
- When the install finishes, launch UEFN from the launcher.
Expected Result
The launcher should install UEFN’s editor component (including FortniteGame/FortniteGame.uproject and Content/Internationalization), and UEFN should open to the project browser.
Observed Result
The launcher drops UEFN’s components on every install, update, and verify, so it resolves no install tags for UEFN:
LogEoshPatcher: Warning: StartTask: BinaryId [fn:1e8bda5cfbb641b9a9aea8bd62285f73:Fortnite_Studio:++Fortnite+Release-43.00-CL-59596594-Windows] — dropped 2 stale DesiredComponents: [A17316661F902216B15E8DAB34ECCD71,BC27D46CFC5347479B3F118F9A31EA06]
LogEoshPatcher: StartTask: BinaryId [fn:1e8bda5cfbb641b9a9aea8bd62285f73:Fortnite_Studio:++Fortnite+Release-43.00-CL-59596594-Windows] — using default components:
LogEoshPatcher: StartTask: BinaryId [fn:1e8bda5cfbb641b9a9aea8bd62285f73:Fortnite_Studio:++Fortnite+Release-43.00-CL-59596594-Windows] — resolved tags:
In the same task, Fortnite itself keeps component A17316661F902216B15E8DAB34ECCD71 (“using validated components”). The UEFN .item manifest ends up with “InstallComponents”: and the editor files are never downloaded. When UEFN launches, it shows “Corrupt/missing files detected”, then “Failed to open descriptor file ../../../FortniteGame/FortniteGame.uproject”, and exits with code 3.
Platform(s)
PC – Windows 11 Home (build 26200), Epic Games Launcher 20.3.7, Fortnite installed on D:\Fortnite\Fortnite\Fortnite
Additional Notes
- UEFN last worked for me in September 2025.
- On Nov 3, 2026 I uninstalled and reinstalled only UEFN (about 25 GB). The same two components were dropped and the same error appeared.
- Turning Fortnite’s “Epic Quality Assets” option on doesn’t help either. Fortnite gets the extra component, but Fortnite_Studio still resolves to .
- Epic Player Support told me to report this here.
- Earlier threads: UEFN won't launch: “Failed to open descriptor file FortniteGame.uproject” and [42.30] UEFN closes on launch ("Failed to open descriptor file") – launcher installs Fortnite_Studio with no components
I can provide the full EpicGamesLauncher.log if needed.