UEFN won't launch: “Failed to open descriptor file FortniteGame.uproject”

General Issues and Bug Reporting
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1

Summary

UEFN does not launch and always shows “Corrupt or missing files detected” followed by “Failed to open descriptor file ../../../FortniteGame/FortniteGame.uproject”. Reinstalling and verifying both Fortnite and UEFN did not fix the issue. Fortnite itself launches normally.

Please select what you are reporting on:

Unreal Editor for Fortnite

What Type of Bug are you experiencing?

Other

Steps to Reproduce

  1. Install UEFN through the Epic Games Launcher.
  2. Launch UEFN.
  3. A message appears saying: “Corrupt or missing files detected. Do you want to verify your installation?”
  4. After continuing, another error appears: “Failed to open descriptor file ../../../FortniteGame/FortniteGame.uproject”
  5. The Crash Reporter then opens and reports that the ICU data directory was not discovered.

Expected Result

UEFN should launch normally after installation and file verification.

Observed Result

UEFN does not launch. It always reports corrupt or missing files, followed by the missing FortniteGame.uproject error and then crashes.

The file FortniteGame.uproject is also not present in E:\Epic Games\Fortnite\FortniteGame\

Platform(s)

PC

Upload an image

corruptormissingfilesdetected.png
corruptormissingfilesdetected.png324×213 7.02 KB
failedtoopendescriptorfile.png
failedtoopendescriptorfile.png453×172 4.23 KB
ue-crashreportclient.png
ue-crashreportclient.png1185×771 51.8 KB

2

I am having the exact same issue. Any luck on resolving it so far?

3

having the same issue here as well. ive dropped two posts, one in june and one just right now, nobody answers :frowning:

5

The status of FORT-1152398 changed to ‘Needs Triage’. We are routing this to the appropriate team for investigation.

6

hi ,

Please check that your PC or network are NOT using Virtual Private Network (VPN), by accident or design.

The Fortnite Game client detects VPN and rather than banning people as before just removes networking files to block this Fortnite/UEFN.

Please also check that your Anti Virus software is not removing parts of UEFN/Fornite files as they regard them as infected.

In the Exclusion section try and add the Fortnite and UEFN binary directories to be stopped from scanning as in past this has caused similar problem.

After adding anything to an Excluded list you must click the three dots next to launch and select Verify to put back the original files

7

Hello. I am experiencing the same issue, and I haven’t been able to resolve it, but I have gathered some more data.

I am using Windows 11, no VPN, no 3rd party AV, just default Windows Defender. (Oh yeah, I made the Defender exclusions you mentioned with no success).

As a side note, I was initially seeing an error about a `tbb12.dll`missing when launching the UEFN exe directly, so I copied the dll from:

C:\Program Files\Epic Games\Fortnite\Engine\Binaries\Win64

to:

C:\Program Files\Epic Games\Fortnite_Studio\FortniteGame\Binaries\Win64

and this resolved that issue about the missing DLL, but then I started to see the same error as others about the FortniteGame.uproject file missing.

I started from a clean state in an attempt to see if that would fix it:

  • I uninstalled Fortnite & UEFN from Epic Launcher.
  • I uninstalled Epic Games Launcher and Epic Online Services from Windows apps/features.
  • I installed Fortnite ver: ++Fortnite+Release-42.30-CL-58557680-Windows.
  • I went to: Fortnite > Manage > Verify, and it succeeded.
  • I then installed UEFN via Epic launcher (same ver as Fortnite i believe).
  • I then again tried: Fortnite > Manage > Verify, and it failed, stating: “Unknown Error - IS-EO-Ins-NotFnd”.
    • UEFN does nothing when clicking Launch; it dies after 2-3 seconds.
    • Fortnite launches normally.
  • I then uninstalled UEFN via Epic Launcher.
  • the Verify procedure for Fortnite succeeded again.

I assume this Verify step is where UEFN is failing. neither the FortniteGame or UnrealEditorFortnite locations in %appdata% generate any logs from this. Maybe the launcher does, I dunno.

I hope this helps!

8

Same issue here on ++Fortnite+Release-42.30-CL-58813929 (Windows 11). UEFN dies 2-3 s after launch with “Failed to open descriptor file ../../../FortniteGame/FortniteGame.uproject”. Reinstalling UEFN, verifying, and Defender exclusions do not help.

I think I found the cause in the launcher log. Every time UEFN (Fortnite_Studio) is installed or verified:

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:

Those two component IDs are the Fortnite base game’s InstallComponents (from its .item manifest in ProgramData\Epic\EpicGamesLauncher\Data\Manifests). The Fortnite_Studio .item ends up with “InstallComponents”: and an empty “ManifestHash”. So UEFN gets installed with no editor content, which explains the missing descriptor and why no UEFN log is written.

Looks like a launcher/EOSH patcher issue: Fortnite_Studio inherits the main app’s components, then drops them as stale. Hope this helps FORT-1152398.