# Need help unpaking a .pak file

**URL:** <https://forums.unrealengine.com/t/need-help-unpaking-a-pak-file/1291656>\
**Category:** Programming & Scripting\
**Tags:** pak, pak-file, unreal-engine, question\
**Created:** [September 11, 2023, 10:24pm UTC](https://forums.unrealengine.com/t/need-help-unpaking-a-pak-file/1291656 "2023-09-11T22:24:00Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![Ivzn](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Ivzn](https://forums.unrealengine.com/u/Ivzn)\
**Post date:** [September 11, 2023, 10:24pm UTC](https://forums.unrealengine.com/t/need-help-unpaking-a-pak-file/1291656/1 "2023-09-11T22:24:01Z")

</div>

So I’m trying to extract a pak file, I have the correct key and engine version but I am stumped.  
I’ve used this command:

```auto
"C:\Program Files\Epic Games\UE_5.1\Engine\Binaries\Win64\UnrealPak.exe" pakchunk0-Windows_0_P.pak -cryptokeys=Crypto.json -Extract C:\Temp >C:\Temp\outputextract.txt

```

This is what I get as Output:

```auto
LogPakFile: Display: Parsing crypto keys from a crypto key cache file
LogWindows: Error: appError called: Assertion failed: SerializeNum >= 0 [File:D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Public\Containers\Array.h] [Line: 1253] 

LogWindows: Error: === Critical error: ===
LogWindows: Error: 
LogWindows: Error: Assertion failed: SerializeNum >= 0 [File:D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Public\Containers\Array.h] [Line: 1253] 
LogWindows: Error: 
LogWindows: Error: [Callstack] 0x00007ff85b8302a9 UnrealPak-PakFileUtilities.dll!operator<<() []
LogWindows: Error: [Callstack] 0x00007ff85b862239 UnrealPak-PakFileUtilities.dll!FPakEntry::Serialize() []
LogWindows: Error: [Callstack] 0x00007ff85b8483ed UnrealPak-PakFileUtilities.dll!ExtractFilesFromPak() []
LogWindows: Error: [Callstack] 0x00007ff85b843bce UnrealPak-PakFileUtilities.dll!ExecuteUnrealPak() []
LogWindows: Error: [Callstack] 0x00007ff7da15be27 UnrealPak.exe!wmain() []
LogWindows: Error: [Callstack] 0x00007ff7da15ce2c UnrealPak.exe!__scrt_common_main_seh() []
LogWindows: Error: [Callstack] 0x00007ff884fa7614 KERNEL32.DLL!UnknownFunction []
LogWindows: Error: [Callstack] 0x00007ff885c026b1 ntdll.dll!UnknownFunction []
LogWindows: Error: 
LogWindows: Error: 
LogWindows: Error: 
LogWindows: Error: 

```

I am extremely stumped and don’t know what to do to extract. Anyone can help?