Tutorial How to unpack and repack Unreal Engine 4 files

masagrator

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Note: Check "Important Posts" for BETA releases.

Because i couldn't find any tutorial for this, i made my own package. This tutorial doesn't include how to unpack NSP, XCI or NCA. It's for people who already knows that. F.e.
https://gbatemp.net/threads/how-to-easy-extract-game-files-from-nsp-xci.534724/

This tutorial is made purposely for mount point ../../../ which is default for Switch games. More info in tutorial.
It may look rough, but it's easy to remember after few attempts.
If something is not working, write post.
English purists should run away. It will not be a plausible text. :D

RequirementsCheck version of packageUnpackPack filesCreating patchExceptionsDecryptionThanksTricks & Tips

  1. What you need to download:
    - Package "UnrealPakSwitch.zip" from attachments and unpack it.
    - Notepad++ (or any other text editor with Perl regular expressions)
    - Python 2 or 3
    - Unreal Engine 4.19.2 (for v4 *.pak), Unreal Engine 4.20.3 (for v5 *.pak), Unreal Engine 4.21.2 (for v7 *.pak), Unreal Engine 4.22.3 (for v8 *.pak), Unreal Engine 4.24.3 (for v8.23 *.pak), Unreal Engine 4.25.4 (for v9 *.pak), Unreal Engine 4.26.2 (for v11 *.pak), Unreal Engine 4.27.x (for v11.27 *.pak). For complete pack you need to download eight of them.

    My package lacks UnrealPak.exe which is licensed, but free to use. That's why I don't upload them.
    After download each respected Unreal Engine you can find UnrealPak.exe in:
    1. X:\Program Files\Epic Games\UE_4.19\Engine\Binaries\Win64\unrealpak.exe
    2. X:\Program Files\Epic Games\UE_4.20\Engine\Binaries\Win64\unrealpak.exe
    3. X:\Program Files\Epic Games\UE_4.21\Engine\Binaries\Win64\unrealpak.exe
    4. X:\Program Files\Epic Games\UE_4.22\Engine\Binaries\Win64\unrealpak.exe
    5. X:\Program Files\Epic Games\UE_4.24\Engine\Binaries\Win64\unrealpak.exe
    6. X:\Program Files\Epic Games\UE_4.25\Engine\Binaries\Win64\unrealpak.exe
    7. X:\Program Files\Epic Games\UE_4.26\Engine\Binaries\Win64\unrealpak.exe
    8. X:\Program Files\Epic Games\UE_4.27\Engine\Binaries\Win64\unrealpak.exe


    For third point (UE_4.21) you need to copy with unrealpak.exe also DLLs and other (treat UnrealPak.exe and all files below as one if you will follow Exceptions tab):
    Code:
    UnrealPak-BuildSettings.dll
    UnrealPak-Core.dll
    UnrealPak-Json.dll
    UnrealPak-PakFile.dll
    UnrealPak-PakFileUtilities.dll
    UnrealPak-Projects.dll
    UnrealPak.modules

    For fourth point (UE_4.22) you need additional files:
    Code:
    UnrealPak-BuildSettings.dll
    UnrealPak-Core.dll
    UnrealPak-Json.dll
    UnrealPak-PakFile.dll
    UnrealPak-PakFileUtilities.dll
    UnrealPak-Projects.dll
    UnrealPak.modules
    UnrealPak-RSA.dll

    For fifth point (UE_4.24) and sixth point (UE_4.25) you need additional files:
    Code:
    UnrealPak-BuildSettings.dll
    UnrealPak-Core.dll
    UnrealPak-DerivedDataCache.dll
    UnrealPak-Json.dll
    UnrealPak-PakFile.dll
    UnrealPak-PakFileUtilities.dll
    UnrealPak-Projects.dll
    UnrealPak.modules
    UnrealPak-RSA.dll
    UnrealPak-TraceLog.dll


    For seventh point (UE_4.26) you need additional files:
    Code:
    UnrealPak-BuildSettings.dll
    UnrealPak-Core.dll
    UnrealPak-DerivedDataCache.dll
    UnrealPak-Json.dll
    UnrealPak-PakFile.dll
    UnrealPak-PakFileUtilities.dll
    UnrealPak-Projects.dll
    UnrealPak.modules
    UnrealPak-RSA.dll
    UnrealPak-SSL.dll
    UnrealPak-TraceLog.dll

    For eighth point (UE_4.27) you need additional files:
    Code:
    UnrealPak-Analytics.dll
    UnrealPak-BuildSettings.dll
    UnrealPak-Core.dll
    UnrealPak-CoreUObject.dll
    UnrealPak-DerivedDataCache.dll
    UnrealPak-Json.dll
    UnrealPak-PakFile.dll
    UnrealPak-PakFileUtilities.dll
    UnrealPak-Projects.dll
    UnrealPak.modules
    UnrealPak-RSA.dll
    UnrealPak-SSL.dll
    UnrealPak-TraceLog.dll

    For each one version you need to copy UnrealPak.exe to correct folder of my package:
    1. UnrealPakSwitch\v4\2\3\UnrealPak.exe
    2. UnrealPakSwitch\v5\2\3\UnrealPak.exe
    3. UnrealPakSwitch\v7\2\3\UnrealPak.exe (+ other files)
    4. UnrealPakSwitch\v8\2\3\UnrealPak.exe (+ other files)
    5. UnrealPakSwitch\v8.23\2\3\UnrealPak.exe (+ other files)
    6. UnrealPakSwitch\v9\2\3\UnrealPak.exe (+ other files)
    7. UnrealPakSwitch\v11\2\3\UnrealPak.exe (+ other files)
    7. UnrealPakSwitch\v11.27\2\3\UnrealPak.exe (+ other files)

    You can now uninstall Unreal Engine(s) (except if you need Oodle support - read "Oodle decompression" in "Tricks & Tips" before continuing) - there are no more needed

    WARNING!
    UnrealPak for some paks shows error about not detecting some plugin. In most cases it's not needed, just ignore it and it will continue.
  2. Archives are mostly in romfs/******/Content/Paks as *.pak files
    ****** - project name made by devs. It's devs choice (for example Octopath has "Kingship"), but most games have one folder in romfs

    1. Copy *.pak file you want to check to unpacked UnrealPakSwitch folder.
    2. Drag and drop your file to "1. check.cmd"
    It will show
    Code:
    Version: X
    Where X is a version of your package.
  3. If you know what version you have, then drag and drop your *.pak file to
    Code:
    version 4 - "unpack-v4.cmd"
    version 5 - "unpack-v5.cmd"
    version 7 - "unpack-v7.cmd"
    version 8 - "unpack-v8.cmd"
    version 8.23 - "unpack-v8-23.cmd"
    version 9 - "unpack-v9.cmd"
    version 11 or 11.27 - "unpack-v11.cmd" or "unpack-v11-27.cmd" (this is because UE 4.27 made breaking changes to pak files without changing header struct, which makes it impossible to differentiate between 11 and 11.27 from header alone).

    They create "lista.txt" in UnrealPakSwitch folder which contains info about all files. It will be needed for packing archive.
    Don't press key to continue. First open "lista.txt" and check if there is a line
    Code:
    LogPakFile: Display: Mount point ../../../
    If it's correct, press any key to continue. If it's not (something different after Mount point or lack of it), close window and go to Exceptions tab.

    After some time it will unpack all files in most cases to 2 folders:
    - Engine
    - ****** (yes, the same ****** as from previous tab)

    ****** contains assets. Engine should not be modified unless you know what you are doing.
  4. First we need to edit lista.txt with Notepad++
    1. Delete those lines (don't worry if one or more lines are missing)
    Code:
    LogPaths: Warning: No paths for game localization data were specifed in the game configuration.
    LogInit: Warning: No paths for engine localization data were specifed in the engine configuration.
    LogPakFile: Display: Using command line for crypto configuration
    LogPakFile: Display: Added 0 entries to add to pak file.
    LogPakFile: Display: Mount point ../../../

    2. Delete last three lines. It will look something like this (quantity of files, size and seconds may differ):
    Code:
    LogPakFile: Display: 103018 files (1944681023 bytes), (1944681023 filtered bytes).
    LogPakFile: Display: Unreal pak executed in 2.605882 seconds
    Third line is empty (CMS of this forum is deleting it, but you can see it in quote mode), you need to delete those three lines.

    3. Run "Find & Replace" (Ctrl+H), Check "Wrap Around" and "Regular Expression"
    Przechwytywanie.PNG
    4.1. For Find what: paste
    Code:
    LogPakFile: Display: "
    Replace with:
    Code:
    "../../../
    Yes - our mount point with quotation mark at the beginning.
    Click Replace All

    4.2. For Find what: paste
    Code:
    " offset: (.*)$
    Replace with:
    Code:
    "
    Click Replace All

    And save.
    Now we have file ready to use for our packing.

    5. Drag and drop "lista.txt" to the same version that original pack was:
    Code:
    version 4 - "pack-v4.cmd"
    version 5 - "pack-v5.cmd"
    version 7 - "pack-v7.cmd"
    version 8 - "pack-v8.cmd"
    version 8.23 - "pack-v8-23.cmd"
    version 9 - "pack-v9.cmd"
    version 11 - "pack-v11.cmd"
    version 11.27 - "pack-v11-27.cmd"

    It will create "newpak.pak" inside UnrealPakSwitch folder. Rename it to name of original *.pak file.
  5. You can create *.pak file that will be treated as patch and doesn't need files that are the same as in original *.pak files.
    1. You need to done "Pack files" tab 1-4.2, ignore 5th point.
    2. Now you need to delete from lista.txt every line that contains path to not-edited file and save lista.txt.
    3. Drag and drop "lista.txt" to the same version that original *.pak was:
    Code:
    version 4 - "pack-v4.cmd"
    version 5 - "pack-v5.cmd"
    version 7 - "pack-v7.cmd"
    version 8 - "pack-v8.cmd"
    version 8.23 - "pack-v8-23.cmd"
    version 9 - "pack-v9.cmd"
    version 11 - "pack-v11.cmd"
    version 11.27 - "pack-v11-27.cmd"

    It will create "newpak.pak" inside UnrealPakSwitch folder. Rename it to name of original *.pak file, but add at the end of filename
    Code:
    _p
    For example
    Code:
    Kingship-Switch.pak -> Kingship-Switch_p.pak
    And put it to the same folder as was your original *.pak

    Not every game accepts patches in this form. For now i found only Octopath Traveler that crash when you try to put *.pak file without proper name, it needs to be named like this
    Code:
    Kingship-Switch_1_P.pak
    Kingship-Switch_2_P.pak
    etc.
  6. Now we need to consider 2 cases: either just your mount point is different or your pak is encrypted. If in lista.txt there is anything about encryption, go to "Decryption" tab. Else continue in this tab.

    Sometimes mount point can be different and my package needs to be slightly modified if you don't want to make mess. It most cases it means that this *.pak archive is additional to other *.pak file(s) and is "inside" one of them, so after unpacking it will look different than Engine and ****** folders. You can check it in "lista.txt"
    Default mount point is ../../../ which is "3 folders before", that's why i put UnrealPak.exe to such weird combination of folders.
    Mount point is saved in archive properties and if it's not preserved, game will show error.

    For example:

    If it will be version 4 package with mount point ../../King/Sample/:
    1. You need to move UnrealPak.exe from v4\2\3 to v4\2\ (only two folders back)
    2. Change in pack-v4.cmd
    Code:
    v4\2\3\UnrealPak.exe ..\..\..\newpak.pak
    to
    Code:
    v4\2\UnrealPak.exe ..\..\newpak.pak
    and in unpack-v4.cmd
    Code:
    v4\2\3\UnrealPak.exe
    to
    Code:
    v4\2\UnrealPak.exe

    Unpacked folders needs to be moved to
    Code:
    UnrealPakSwitch\King\Sample

    For 4.4 in Pack files tab you will need to change Replace with: to
    Code:
    ../../King/Sample/

    Now you can go back to previous tabs and continue with knowledge that some files are now different, but steps are the same if you take informations from here and change in previous tabs.
  7. In some cases devs decided to encrypt index of pak file and because of that we can't easily unpack all files. Some multiplatform games are using the same key, so if your game has also PC version, try to find key on google (there are sites specializing in extracting keys from PC exes). But there is a method how to get this decryption key from Switch executable. For more go here:
    https://gbatemp.net/threads/how-to-extract-decryption-key-for-unreal-engine-4-pak-files.574916/

    Don't share any keys here in this topic as it is violation of rules.

    If you have key in 32 bytes hex format like this:
    Code:
    1211345678901234432109876543210036363636363636363636363636363621
    We need to convert it to Base64. There are many sites converting hex to Base64, link to used by me:
    https://base64.guru/converter/encode/hex

    So in my case I got
    Code:
    EhE0VniQEjRDIQmHZUMhADY2NjY2NjY2NjY2NjY2NiE=

    Now go to UnrealPakSwitch folder, edit "crypto.json" and replace
    Code:
    DUMMY
    with our Base64 key and save it. This is how it will look in the end

    Code:
    {
      "$types": {
        "UnrealBuildTool.EncryptionAndSigning+CryptoSettings, UnrealBuildTool, Version=4.0.0.0, Culture=neutral, PublicKeyToken=null": "1",
        "UnrealBuildTool.EncryptionAndSigning+EncryptionKey, UnrealBuildTool, Version=4.0.0.0, Culture=neutral, PublicKeyToken=null": "2"
      },
      "$type": "1",
      "EncryptionKey": {
        "$type": "2",
        "Name": null,
        "Guid": null,
        "Key": "EhE0VniQEjRDIQmHZUMhADY2NjY2NjY2NjY2NjY2NiE="
      },
      "SigningKey": null,
      "bEnablePakSigning": false,
      "bEnablePakIndexEncryption": true,
      "bEnablePakIniEncryption": true,
      "bEnablePakUAssetEncryption": false,
      "bEnablePakFullAssetEncryption": false,
      "bDataCryptoRequired": true,
      "SecondaryEncryptionKeys": []
    }

    Go back to "Unpack" tab but instead of using "unpack-*****.cmd" we need to use "unpack-encrypted-*****.cmd".

  8. Thanks to panzi for u4pak.py (that i slightly modified for this package)
    https://github.com/panzi/u4pak
  9. It will be updated with new informations in time.

    ufontuexp, uasset, ubulklocresOodle compressionZSTD compressionOther tutorials

    1. *.ufont file is ttf font with only changed extension.
      If your file is f.e.
      Code:
      Ariadna.ufont
      change name to
      Code:
      Ariadna.ttf
      You can edit it without worry if you don't change config of this font inside font editor.
    2. If asset contains only uexp and uasset:
      *.uexp is archive for data - in default it's not compressed nor encrypted, but it can be cofigured by devs if they want to modify the way how files are packed.
      *.uasset has informations about files inside uexp - their filenames and references - and how big is *.uexp file:
      Code:
      *size in bytes*-4 converted to Hex Little Endian
      f.e.
      1966078-4 = FAFF1D

      If asset contains uexp, uasset and ubulk:
      *.uasset has informations about files inside uexp - their filenames and references - and how big is uexp
      *.uexp is archive for Editor data, it contains data about ubulk size and thumbnail representing asset
      *.ubulk contains raw asset without any additional info

      If you change size of *.uexp file and you don't change value inside *.uasset, game will not load.
      If you want to serialize informations included in them (f.e. stats of equipment), I recommend John Wick Parse. It extracts supported data to json files:
      https://github.com/SirWaddles/JohnWickParse/releases
      and this tool that seems to have better support for blueprints:
      https://gitlab.com/alex4401/uasset-data-extractor
    3. *.locres - localization files. This is default way of saving strings, but it's not often used by devs. They prefer to create their own format and put to *.uexp file (f.e. Octopath Traveler).
    4. Some games may use oodle compression for pak files (v8+ can generate filelist with info about used compression method, if it's not custom).
      Unreal Engine 4.27 version has added Oodle for free, so you can use that to unpack v11.27 PAKs and older than v11 (because of code conflict UnrealPak 4.27 doesn't support v11 PAKs).
      You must go to:
      Code:
      X:\Program Files\Epic Games\UE_4.27\Engine\Plugins\Compression\

      Copy folder "OodleData" to "v11.27" folder in UnrealPakSwitch folder.
      For unpacking v11 you can use QuickBMS
      https://aluigi.altervista.org/quickbms.htm
      With this script
      https://gbatemp.net/threads/unpacking-sao-fatal-bullet-pak.545478/#post-8748129
      You don't need oodle for packing, default compression (zlib) will be readable by game, so you can follow this tutorial for packing files.
    5. Some games may use zstd compression for pak files (v8 can generate filelist with info about used compression method, if it's not custom).
      Unrealpak is then not usable without compiling zstd plugin by yourself. But for unpacking you can use QuickBMS
      https://aluigi.altervista.org/quickbms.htm
      With this script
      https://gbatemp.net/threads/how-to-...al-engine-4-files.531784/page-10#post-9380618
      You don't need zstd for packing, default compression (zlib) will be readable by game, so you can follow this tutorial for packing files.
    6. How to swap audio in Unreal Engine 4 games
      https://gbatemp.net/threads/how-to-swap-audio-in-unreal-engine-4-games.535516/

      Tool for extracting and making textures compatible with Switch
      https://gbatemp.net/threads/noesis-mod-tiling-texture-for-ue4.535571/
 

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  • UnrealPakSwitchv9.zip
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masagrator

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Does it mean resolutions and framerate modifications?
I don't know. I tried to modify FPS for Octopath Traveler, there were 3 files with FPS value, I have changed it and it does nothing. There are many graphic settings, but I don't know if they really work. Maybe it depends on each game.
 
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Kirby567fan

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Yoshi Crafted World demo could be an interesting case since in portable mode resolution really drops and the agressive depth of field really make those background so blurry. Will try various games tomorrow and I will give you result and also thanks for answering.
 

Nazosan

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So maybe I'm missing something really really obvious, but where can I actually get UnrealPak? I presume it's part of a main SDK or whatever, but I'm not even sure where that is. Is it at all possible to get it without downloading something huge even if so?
 

masagrator

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So maybe I'm missing something really really obvious, but where can I actually get UnrealPak? I presume it's part of a main SDK or whatever, but I'm not even sure where that is. Is it at all possible to get it without downloading something huge even if so?
Read Requirements tab carefully. It's all there.
It's possible, but not legal.
 
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masagrator

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Actually unpacking v4 games with v5 works for me. Will test packing now.
I know. But it's because there are many versions that I needed to split it for pack.cmd, so if someone download only one Unreal Engine correct for their *.pak version, they will always have unpack.cmd to use.

And there is no chance that higher version *.pak will work on lower Unreal Engine 4 game (with one exception). You can try to pack lower version for higher version game, but probably will be the same result.

For v5 & v4 there are no differences except version in one byte for one file packed. For more files we have more differences.
v7 has more differences even for one file.

v4 worked for v5 game with one file as patch. So v5 should work for v4 with one file. v7 for v5 - crash.
v4 may not work for v5 and vice versa with more than one file.
 
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IHOP

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I can't be the only one wanting to see the OOT Unreal Engine remakes on switch. I don't even know if that's possible with this but lmao it'd be freaking awesome
 

masagrator

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maybe octopath traveler crash because it expect the extra PAK to be named as something special? when i looked at the files, i think i found a text something like "Kingship-Switch-01.pak"
I don't think so. I have tried to pack gametext from main pack to second pack with other files that were already there and I've put it as second pak. Result: crash. I think they implented a plugin that checks files inside *.pak archive with assets list inside them.
 
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masagrator

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Ok, my bad. It turns out that for Octopath patch needs to be named like the smallest file, but with next number and cannot be putted to subfolder.
So now it works with Kingship-Switch_1_P.pak

@orangpelupa If you are interested.
 
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masagrator

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Yes, first time it crashed system, but from second time it works flawlessly. I'm translating game, I've packed only modified fonts and texts and it works.
 

Kirby567fan

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Yes, first time it crashed system, but from second time it works flawlessly. I'm translating game, I've packed only modified fonts and texts and it works.
Thats cool. Im also trying to modifie some games's resolution and graphics so they can profite from OCing.
 

masagrator

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Updated package with support for version 8 of Unreal Engine 4.22.
Modified by me u4pak.py will show
Code:
Version: 8 or higher

As there is no version header from this iteration of Unreal Engine, for now we can recognize it only because there is no other version of UnrealPak that it's hiding it.
And for today newest version is "8", "higher" is only for future use when will be newer iterations of UnrealPak.
 
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dnasdw

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There is no problem in Ocotopath Traveler's patch paks.
But different version(between v1.0.0 and v1.0.2) will crash.

reference url on github: /dnasdw/game_patches/releases/tag/octopath_Switch
 

Shinigati

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There is a problem with PixArk getting the following error:

LogWindows: Error: === Critical error: ===
LogWindows: Error:
LogWindows: Error: Fatal error: [File:D:\Build\++UE4\Sync\Engine\Source\Runtime\Core\Private\GenericPlatform\GenericPlatformMemory.cpp] [Line: 212]
LogWindows: Error: Ran out of memory allocating 18446744071819873553 bytes with alignment 0

edit: please ignore my ignorance, i was dragging the file onto "pack" instead of "unpack" batch file.
 
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