Hello all, i new to all this unreal stuff, what i trying to figure out is, i run a server for citadel, and wanted to edit and customize server to be one of a kind, some servers are modded a bit, so wanted do same. i downloaded the 5 gig .pak file from server, to edit all at home, then re upload when done. Issues are, that nothing i use or try, lets me edit a pak file, i got a viewer that i am able to see all the file lines and goodies, and i see where i need do my changes, but nothing lets me edit it. Yesterday i downloaded the unreal engine 4, 20 gigs worth from epic games, but still, i cant see how to open this .pak file. google says use a tool like 7 zip or similar, any tool i try, just says error, unable open this. what am i missing?? thanks all
The .pak files are not meant to be edited and may in fact be encrypted in some way to prevent abuse.
You should search around to see if there is some sort of mod SDK for the game.
hello, you can open the pak file using UnrealPak.exe (in UE_4.21\Engine\Binaries\Win64\UnrealPak.exe)
once you open UnrealPak.exe it instantly closes
in the folder, open a command prompt (that is executing in the folder)
if you can’t then follow this: press Win+r then type “cmd”, then type the drive letter that you have installed unreal engine in EG:“f:”, then type “CD [YourUnrealEngineFolder]” (make sure your in the Win64 folder) 
then type UnrealPak.exe [PakFileDirectory] -Extract [ExtractionDestinationDirectory]
and then wait for unrealpak to finish
once finished you will see 3 file types in the extraction directory : .uasset .ubulk .uexp
now its up to you to figure out how to open these files :rolleyes:
these are all of UnrealPak.exe’s commands :
UnrealPak [PakFilename] -Test
UnrealPak [PakFilename] -List -ExcludeDeleted]
UnrealPak [PakFilename] [GameUProjectName] [GameFolderName] -ExportDependencies=[OutputFileBase] -NoAssetRegistryCache -ForceDependsGathering
UnrealPak [PakFilename] -Extract [ExtractDir]
UnrealPak [PakFilename] -Create=[ResponseFile] [Options]
UnrealPak [PakFilename] -Dest=[MountPoint]
UnrealPak [PakFilename] -Repack -Output=Path] -ExcludeDeleted] [Options]
UnrealPak GenerateKeys=[KeyFilename]
UnrealPak GeneratePrimeTable=[KeyFilename] -TableMax=[N]]
UnrealPak [PakFilename1] [PakFilename2] -diff
UnrealPak [PakFolder] -AuditFiles -OnlyDeleted] -CSV=[filename]]
UnrealPak [PakFilename] -WhatsAtOffset [offset1] [offset2] [offset3] …]
UnrealPak -TestEncryption
Options:
-blocksize=[BlockSize]
-bitwindow=[BitWindow]
-compress
-encrypt
-order=[OrderingFile]
-diff (requires 2 filenames first)
-enginedir (specify engine dir for when using ini encryption configs)
-projectdir (specify project dir for when using ini encryption configs)
-encryptionini (specify ini base name to gather encryption settings from)
-extracttomountpoint (Extract to mount point path of pak file)
-encryptindex (encrypt the pak file index, making it unusable in unrealpak without supplying the key)
-compressor=[DllPath] (register a custom compressor)
-overrideplatformcompressor (override the native platform compressor)