[42.30] UEFN closes on launch ("Failed to open descriptor file") – launcher installs Fortnite_Studio with no components

General Issues and Bug Reporting
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1

Summary

Since 42.30, UEFN closes 2-3 seconds after launch with “Failed to open descriptor file ../../../FortniteGame/FortniteGame.uproject”. Fortnite itself launches normally. Possibly related to FORT-1152398 (UEFN won't launch: “Failed to open descriptor file FortniteGame.uproject”), but that report is from an earlier build and is still in “Needs Triage”, so I’m filing a detailed report for 42.30.

Please select what you are reporting on:

Unreal Editor for Fortnite

What Type of Bug are you experiencing?

Stability

Steps to Reproduce

  1. Install Fortnite (++Fortnite+Release-42.30-CL-58813929-Windows) from the Epic Games Launcher.
  2. Install Unreal Editor for Fortnite from the Launcher.
  3. Click Launch on UEFN.

Expected Result

UEFN opens the project browser.

Observed Result

A “Corrupt or missing files detected” prompt appears, then “Failed to open descriptor file ../../../FortniteGame/FortniteGame.uproject”, and the editor closes. No UEFN log is written.

Evidence from EpicGamesLauncher.log (repeats on every install/verify of UEFN):
LogEoshPatcher: Warning: StartTask: BinaryId [fn:1e8bda5cfbb641b9a9aea8bd62285f73:Fortnite_Studio:++Fortnite+Release-42.30-CL-58813929-Windows] — dropped 2 stale DesiredComponents: [A17316661F902216B15E8DAB34ECCD71,BC27D46CFC5347479B3F118F9A31EA06]
LogEoshPatcher: StartTask: … — using default components:
LogEoshPatcher: StartTask: … — resolved tags:

The two dropped component IDs are the Fortnite base game’s InstallComponents. The resulting Fortnite_Studio .item manifest (ProgramData\Epic\EpicGamesLauncher\Data\Manifests) has “InstallComponents”: and “ManifestHash”: “”. It looks like UEFN is installed without its editor content.

Already tried, without success: verify Fortnite and UEFN, uninstall/reinstall UEFN, Windows Defender exclusions, no VPN running, PC restart. Other users in the thread above report the same after a full clean reinstall of Fortnite and the Launcher.

Platform(s)

Build: ++Fortnite+Release-42.30-CL-58813929-Windows

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Additional Notes

I can provide the full EpicGamesLauncher.log privately if needed.

3

hi all @Flak

This looks like same as thread post

UEFN won’t launch: “Failed to open descriptor file FortniteGame.uproject” - General / Issues and Bug Reporting - Epic Developer Community Forums

This is not an exact duplicate but something to do with “Fortnite_Studio”, because when you look in UE6 there is a problem that somehow need this function and it cannot be loaded because its not available in binary or source to outside world

the missing file “tbb12.dll” only affects 12th Generation Intel chips and in the ue6 source build you have to build it separately!.

4

Thanks for the reply! For info, tbb12.dll is already present in my FortniteGame\Binaries\Win64 folder, so the missing DLL isn’t the cause in my case.

Agreed that this seems related to Fortnite_Studio on Epic’s side: the launcher log shows the UEFN install dropping its components (“resolved tags: ”), so the editor content never gets installed.

Could someone from Epic take a look and link this to FORT-1152398? Thanks!

5

The status of FORT-1170468 changed to ‘Needs Triage’. We are routing this to the appropriate team for investigation.

6

I’m experiencing the same issue with UEFN 42.30 on Windows 11.

Fortnite launches normally, but UEFN closes approximately 2 seconds after launching and the Epic Games Launcher returns to the “Launch” button.

I also noticed:

  • FortniteGame.uproject is missing from my Fortnite_Studio/FortniteGame folder.

  • The launcher logs show dropped 1 stale DesiredComponents and using default components: [].

  • Fortnite verification previously failed with error IS-EO-Ins-NotFnd.

I’ve tried restarting Windows and verifying the installation, but UEFN still won’t launch.

Is there a confirmed workaround or fix for this issue?

7

Hi, did you solve it? I am having the same issue

8

Hi @wowkill my workaround until Epic officials fix is 42.40 possibly.

Unable to launch fortnite through UEFN after installing the new EGL or latest update - General / Issues and Bug Reporting - Epic Developer Community Forums