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. Use DBI or emulators romfs browser.

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.

RequirementsCheck version of packageUnpackPack filesCreating patchExceptionsDecryptionThanksTricks & Tips

1. What you need to download:
   - Package "UnrealPakSwitchv9.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 4.27.2 (for v11.27 *.pak). For complete pack you need to download eight of them.
   
   
   Additional note If you want to extract PAK, download just newest version (Unreal Engine 4.27.2) since UnrealPak unpacking is backwards compatible (only exclusion is that v11 PAKs are not fully supported by v11.27 unrealPak).
   For packing files usually you can use unrealPak version that matches your PAK version or older, so you can use oldest Unreal Engine 4 (4.19.2) to pak your mods and it should work for 99% of cases.
   Remember that's not a rule since developers can change how PAKs are packed or read individually.
   Tutorial is explaining how to extract and make PAKs "properly", though you can skip some parts of it if you know what you are doing.
   
   
   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):
   
   Spoiler: File list

   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:
   
   Spoiler: File list

   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:
   
   Spoiler: File list

   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:
   
   Spoiler: File list

   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:
   
   Spoiler: File list

   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
   

   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
   

   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 10 - "unpack-v11-27.cmd" (because 10 is unofficial version, we can use as newest tool as possible for Oodle support)
   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
   

   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. To pack files we need Engine folder unpacked from one of original PAKs. Usually you can find it it any game PAK that is first in alphanumerical order, usually with name starting at "pakchunk0". UnrealPak reads files from this folder before starting reading file list. Not having this folder with correct files will result in error.
   Remember than UnrealPak always creates Engine folder when used if it doesn't exist, so having this folder is not equal to that you have all necessary files.
   
   First we need to edit lista.txt with Notepad++
   1. Delete those lines (don't worry if one or more lines are missing)
   

   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):
   

   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"
   
   4.1. For Find what: paste
   

   LogPakFile: Display: "

   Replace with:
   

   "../../../

   Yes - our mount point with quotation mark at the beginning.
   Click Replace All
   
   4.2. For Find what: paste
   

   " offset: (.*)$

   Replace with:

   "

   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:
   

   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 10 - "pack-v9.cmd" (because 10 is unofficial version, we need to step down by one version)
   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 from beginning to point 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:
   

   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 10 - "pack-v9.cmd" (because 10 is unofficial version, we need to step down by one version)
   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
   

   _p

   For example
   

   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
   

   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
   

   v4\2\3\UnrealPak.exe ..\..\..\newpak.pak

   to
   

   v4\2\UnrealPak.exe ..\..\newpak.pak

   and in unpack-v4.cmd
   

   v4\2\3\UnrealPak.exe

   to
   

   v4\2\UnrealPak.exe

   
   Unpacked folders needs to be moved to
   

   UnrealPakSwitch\King\Sample

   
   For 4.4 in Pack files tab you will need to change Replace with: to
   

   ../../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:
   

   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
   

   EhE0VniQEjRDIQmHZUMhADY2NjY2NjY2NjY2NjY2NiE=

   
   Now go to UnrealPakSwitch folder, edit "crypto.json" and replace

   DUMMY

   with our Base64 key and save it. This is how it will look in the end
   
   

   {
     "$types": {
       "UnrealBuildTool.EncryptionAndSigning+CryptoSettings, UnrealBuildTool, Version=4.0.0.0, Culture=neutral, PublicKeyToken=null": "1",
       "UnrealBuildTool.EncryptionAndSigning+EncryptionKey, UnrealBuildTool, Version=4.0.0.0, Culture=neutral, PublicKeyToken=null": "2"
     },
     "$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.
      

      Ariadna.ufont

      change name to
      

      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:
      

      *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:
      

      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/

 

[Steakmaster]

Is there a way to pak files with Oodle compression? It seems like some games requires Oodle compressed pak for the game to read the pak.

 

[masagrator]

Is there a way to pak files with Oodle compression? It seems like some games requires Oodle compressed pak for the game to read the pak.

Never saw such game. Provide an example.

 

[zerlkung]

On v11.27 bat file script is have [space bar] before Engine it right sir?

xcopy /i /e /q /c /y v11.27\OodleData\ Engine\Plugins\Compression\OodleData > NUL 2> NUL

 

[masagrator]

On v11.27 bat file script is have [space bar] before Engine it right sir?

xcopy /i /e /q /c /y v11.27\OodleData\ Engine\Plugins\Compression\OodleData > NUL 2> NUL

If you are asking about should space be there - the answer is "yes". Try to delete it and xcopy will throw error (which is nulled in this script anyway, so you won't see it without deleting nulling errors)

 

[Steakmaster]

Never saw such game. Provide an example.

When the game was 4.26.2, the game read the modified paks without issues.
However, when the game got updated to UE 4.27.2 + Oodle compression.

-The game act as if the pak doesn't exist/cant read the pak.
-When I unpack the modified pak, it seems like everything is in order. All file exists within the pak.
-The error is similar to me just deleting/renaming an unmodified pak.

The game is called The Cycle Frontier, me and my friends are trying to fully translate the game to Bahasa Melayu. It seems that the game does not read the paks at all. Which would equal in a UE Error crash.

 

[masagrator]

When the game was 4.26.2, the game read the modified paks without issues.
However, when the game got updated to UE 4.27.2 + Oodle compression.

-The game act as if the pak doesn't exist/cant read the pak.
-When I unpack the modified pak, it seems like everything is in order. All file exists within the pak.
-The error is similar to me just deleting/renaming an unmodified pak.

The game is called The Cycle Frontier, me and my friends are trying to fully translate the game to Bahasa Melayu. It seems that the game does not read the paks at all. Which would equal in a UE Error crash.

From what I see this game didn't release on Switch. So it's out of scope for this tutorial.
Only I can say that yes - it's possible to pack with Oodle compression, but only for v11. 27/UE4.27.
Check help in unrealpak.exe how to set type of compression.

 

[Steakmaster]

From what I see this game didn't release on Switch. So it's out of scope for this tutorial.
Only I can say that yes - it's possible to pack with Oodle compression, but only for v11. 27/UE4.27.
Check help in unrealpak.exe how to set type of compression.

Have you had a problem with any switch game that is based on UE4.27, and not recognizing the modified pak file before?
It could be a mount point issue where the game aren't able to find the localization/asset files in the packed pak.

I'm currently using the UnrealPakSwitchv9, as it worked on the same game on UE4.26
I'll try using the v10BETAv3 to see if there's any changes.

I have no idea why the game recognized the paks in UE4.26 but not in UE4.27 tho.

 

[masagrator]

Have you had a problem with any switch game that is based on UE4.27, and not recognizing the modified pak file before?

I had crashes when PAKs didn't have proper names (like in Octopath Traveler). Never that it wasn't recognized at all.

 

[Steakmaster]

I had crashes when PAKs didn't have proper names (like in Octopath Traveler). Never that it wasn't recognized at all.

I used QuickBMS to unpack instead of this tool, and I think I've found the problem now.
Do you know how to generate a lista.txt with QuickBMS so I can repack with this tool?

 

[Steakmaster]

I think it might be a mounting issue when packing. I thought 4.26.2 has the same mount point as 4.27.2 tho

 

[Steakmaster]

I did a couple of test, and noticed something. I renamed an original pak file to a random name = iuwehfiwef.pak.
And the game seems to load it up. So it looks like none of my modified pak are even being loaded by the game.

Is there a way to encrypt the paks?
This is the command line to my pack-v11-27.cmd
v11.27\2\UnrealPak.exe ..\..\newpak.pak -Create=%1 -compress -encrypt -encryptindex -aes=64 letter key

 

[Steakmaster]

Ahh nvm, after doing a few experiment. I've managed to encrypt the paks too. Looks like the game wont read any paks that doesn't have a sig file with it. Sig files also ignores modified paks for some reason, changing the name of the modified pak to fit the sig file does not load the pak either. The sig file will only allow the game to read the original pak regardless if you changed the name to something random. = ifweofijwef.pak and ifweofijwef.sig

 

[Eiffel2018]

Never seen utoc and ucas in my life, so I can't help.

Just found them in Various Daylife (TID 0100538017BAC000) and many new games, such as DQ10 offline
I'm struggling with how to disassemble them

 

[Eiffel2018]

Are there any tool to extract this kind of UE4/UE5 files

 

[switchhunter666]

ill look into it and try to see if i can extract them

 

[switchhunter666]

fmodel works
https://fmodel.app/

 

[Eiffel2018]

fmodel works
https://fmodel.app/

Do you know what the AES key is or how to find it?

 

[switchhunter666]

Decryption tab on first page I think

 

[zerlkung]

Are there any tool to extract this kind of UE4/UE5 files
View attachment 327261

I use https://github.com/jashking/UnrealPakViewer can extract .ucas but i don't have any idea to repack.

 

[switchhunter666]

I use https://github.com/jashking/UnrealPakViewer can extract .ucas but i don't have any idea to repack.

It's encrypted and how to repack is on the first page....