# UEFN instant crash

**URL:** <https://forums.unrealengine.com/t/uefn-instant-crash/2128164>\
**Category:** Issues and Bug Reporting\
**Tags:** fortnite-creative, unreal-editor-for-fortnite, fortnite\
**Created:** [November 16, 2024, 3:23pm UTC](https://forums.unrealengine.com/t/uefn-instant-crash/2128164 "2024-11-16T15:23:15Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Lonrot](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Lonrot](https://forums.unrealengine.com/u/Lonrot)\
**Post date:** [November 16, 2024, 3:23pm UTC](https://forums.unrealengine.com/t/uefn-instant-crash/2128164/1 "2024-11-16T15:23:15Z")

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### Summary

For two days since update UEFN instantly crash, already uninstalled and reinstalled UEFN/Fornite, the issue persists.

LoginId:f9cc09a54d0652e46357519bbf49d17d  
EpicAccountId:ecdb6c1ce534434a8c5c62c1e6aea889

Fatal error: [File:D:\build++Fortnite\Sync\Engine\Source\Runtime\PakFile\Private\PakFile.cpp] [Line: 346]  
Corrupt pak index detected on pak file: ../../../FortniteGame/Content/Paks/pakchunk4647optional-WindowsClient.pak

This is the error message:  
UnrealEditorFortnite\_Win64\_Shipping

### Please select what you are reporting on:

Unreal Editor for Fortnite

### What Type of Bug are you experiencing?

Other

### Steps to Reproduce

Launch UEFN exe

### Expected Result

Run properly

### Observed Result

Instant crash

### Platform(s)

Windows 10

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**Author:** ![PLANETAGEEKS](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/planetageeks/32/995218_2.png) [@PLANETAGEEKS](https://forums.unrealengine.com/u/PLANETAGEEKS)\
**Post date:** [November 16, 2024, 4:00pm UTC](https://forums.unrealengine.com/t/uefn-instant-crash/2128164/2 "2024-11-16T16:00:06Z")

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I’M HAVING THE SAME PROBLEM! WERE YOU ABLE TO SOLVE IT?

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**Author:** ![Jimbohalo10](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/jimbohalo10/32/961440_2.png) [@Jimbohalo10](https://forums.unrealengine.com/u/Jimbohalo10)\
**Post date:** [November 16, 2024, 10:13pm UTC](https://forums.unrealengine.com/t/uefn-instant-crash/2128164/3 "2024-11-16T22:13:37Z")

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hi @Lonrot  
Please Need to delete all the files in  
C:\Program Files\Epic Games\Fortnite\FortniteGame\Content\Paks

Then Verify the installation which will take about 45 minutes

[Verify UEFN/Fortnite](https://forums.unrealengine.com/t/urc-exe-and-urc-dll-get-flagged-as-malware-from-microsoft-defender/1802519/4)  
The picture color slides as verification takes place

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**Author:** ![Lonrot](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Lonrot](https://forums.unrealengine.com/u/Lonrot)\
**Post date:** [November 18, 2024, 6:00am UTC](https://forums.unrealengine.com/t/uefn-instant-crash/2128164/4 "2024-11-18T06:00:06Z")

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Thank you so much, I will try it right away!  
UPDATE: That fixed the problem 🙂