Possible Crash When Starting UEFN

Flak · November 1, 2025, 8:11pm

We are aware that some Fortnite developers may experience a crash when starting UEFN. We will let you know when we have more information or a fix.

As a temporary solution please try the following:

Inside the Epic Games Launcher, navigate to the Fortnite client menu with the ellipse (…)
Go to “Options”
Ensure “High Resolution Textures” is checked
Click “Apply”

Jimbohalo10 · November 1, 2025, 10:49pm

hi All,

Please check Epic Games Public Status before trying to start/install the new version 38.00 of UEFN.

If your UEFN crash is like

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Fatal error: [File:Z:\UEVFS\Root\Engine\Source\Runtime\RenderCore\Private\RenderingThread.cpp] [Line: 823]

Rendering thread exception:
Fatal error: [File:Z:\UEVFS\Root\Engine\Source\Runtime\Renderer\Private\ShaderBaseClasses.cpp] [Line: 248]

Failed to find parameter collection buffer with GUID ‘8CC222B44C6842ABBBD7B5A51B4DECE7’ for /Game/TimeOfDay/TODM_Sequence/Materials/Sky/MI_UEFN_Sky_Ch5.MI_UEFN_Sky_Ch5.
Currently 5 listed default instances:
0x000001DCD6B76990: MPC_UIKit_InputFieldCaretColor: 4276CB2D41D48DFD7AE477B6AAB71B67
0x000001DCCCFA3240: MPC_Water: B5A9ACFF4B0499E786A4F981E5B966F6
0x000001DCCD42D9B0: FortniteMaterialParameters: A49449A349668D6F22FD2DA33BB9124E
0x000001DCCD4232A0: Stencil_ID_Definitions: 044A64DD437E451F386E4F8EE322E501
0x000001DD44B800F0: MPC_FrontendUI: 7A32DC7A4DF6A575A68D2C899F3636A5

The line

0x00007ffb110247bf UnrealEditorFortnite-Engine-Win64-Shipping.dll!UnknownFunction

repeats many times

==============================================================

Please follow the past post above, changing the UEFN High Resolution Textures setting in the Epic Games Launcher

After several attempts to log in, UEFN crashed and fell back into the Epic Games launcher… then the EG Launcher WINDOW 11 app closed and could not log in

UEFN will not install correctly from the Launcher on any Windows 11 (eleven) version that needs to run Elevated "Run As Administrator - General / Issues and Bug Reporting

If UEFN 38.00 experiences random crashes. Please uninstall 37.** UEFN and Fortnite.

Then install a new version of 38.00 UEFN and Fortnite.
Afterwards, use verify, as occasionally in the past, this has resolved the issue.

Please wait until the Epic Games Public Status shows all green before attempting to complete the UEFN 38.00 installation, possibly using the information provided in the post above.

Fortnite Login Issues

Resolved - This incident has been resolved.
Nov 2, 03:20 UTC

Follow the original post 1 procedure above before trying to use 38.00 UEFN

Please don’t add random posts on operational problems on this forum

Epic Launcher and UEFN down - General / Issues and Bug Reporting - Epic Developer Community Forums

Please follow the Known Problems thread

Fortnite Ecosystem 38.00 Known Issues Thread - General / Announcements - Epic Developer Community Forums

by setting the status at the bottom of the page from the default.

“You will be notified if someone mentions your @namename or replies to you.”

And in the drop-down, selecting “Watching” will give the thread status

“You will receive notifications because you are watching this topic”

Dormikon · November 2, 2025, 2:51pm

Hi @Flak ; @Jimbohalo10

This workaround worked for me. Thanks so much!

MACKJACK · November 3, 2025, 7:36pm

Was having issues all morning myself, I tried uninstalling UEFN and verifying files etc.
I managed to resolve by uninstalling uefn AND fortnite, and then reinstalling both. I can now work again!

VANGORK · November 4, 2025, 11:11am

UEFN keeps crashing. When loading some projects UEFN crashes and shows the error: Unhandled Exception: EXCEPTION_ACCESS_VIOLATION reading address 0x0000000000000038. I can’t get into some projects. The error persists since the last update. I haven’t found a solution yet.

31Asha · November 4, 2025, 1:47pm

I have the same error

VANGORK · November 5, 2025, 11:28am

(post deleted by author)

Rock_Studio · November 5, 2025, 3:10pm

Please investigate to the EXCEPTION_ACCESS_VIOLATION crash problem, many people can’t start a session or make memory calculation without having UEFN crash every single time, please fix this ASAP or creators can’t update maps!
Unhandled Exception: EXCEPTION_ACCESS_VIOLATION 0x00007ffd00000000

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