Unreal Engine 4/5 Scripting System
Lua scripting system platform, C++ Modding API, SDK generator, blueprint
mod loader, live property editor and other dumping utilities for UE4/5
games.
Link to the original github project: https://github.com/UE4SS-RE/RE-UE4SS

F.A.Q.
Q: Why would I need this?
A: This tool is only needed for loading blueprint mods. Most mods such as texture changes/value changes (e.g. more ammo in a mag, different spawn rates) won't need this. Hopefully, whoever uploads a BP mod on nexus will set this as a requirement or at least include their own version.

Q: Why would I download this from here instead of original github project?
A: Because for BP mods to load in IRR, I had to change some things in the UE4SS files. Unfortunately, these changes can't be pull requested to the original project since they may break something when UE4SS is used with other games. If you still don't trust me, don't worry, I'll document the changes I did so you can get the original version and then change it yourself.

Q: Why didn't you create a fork of the original project on github and released your version there?
A: "I mean, I really tried. This is as good as I can do and I still failed." For some reason, I am unable to clone all required submodules to build the release so there is no reason to fork a project I won't be able to build and release.

Q: Will this version be kept up-to-date with the original version?
A: Not really. At least until IRR switches to Unreal Engine 5.6 I probably will not update this every new release. And when it does switch, I'll kms have to see if UE4SS even supports 5.6 and reupload new version here as soon as they will.

Important Notes
This version was made from the experimental-latest release, UE4SS_v3.0.1-450-g1033902 (Aug 3, 2025) in particular.
This is not a developer version, and it is already configured to interfere with gameplay as little as possible.If you wish to develop your own blueprint mods, download latest developer experimental version from https://github.com/UE4SS-RE/RE-UE4SS/releases/tag/experimental-latest and then implement the changes described below so your mod can actually load (that is if the particular problem I'm fixing won't be fixed already by then).

Changes from the original version
The only reason I'm doing this is that when I downloaded the original version of UE4SS, it wouldn't load any mods after entering Quarry or Bunker maps. Thanks to Nikwazhere and Palworld modding wiki I was able to come up with a solution that does load mods every time you load onto any map. This does mean that mods will load twice on main menu, hideout, lobby and raid results screen. Do I care? Well,

To achieve this, I added following code snippet at the end of the ue4ss\Mods\BPModLoaderMod\Scripts\main.lua file - add this too if you are configuring original version.
RegisterHook("/Script/Engine.PlayerController:ServerAcknowledgePossession", function(Context)
    local ExistingActor = FindFirstOf("Actor")
    if ExistingActor:IsValid() then
        LoadMods(ExistingActor:GetWorld())
    end
end)

There are some configuration changes I made for this version so it works out of the box and doesn't load additional unwanted windows on game startup.
All of those are in ue4ss\UE4SS-settings.ini - find the lines and change the values accordingly if you are configuring original version.[EngineVersionOverride]
MajorVersion = 5
MinorVersion = 4

[Debug]
; Whether to enable the external UE4SS debug console.
ConsoleEnabled = 0
GuiConsoleEnabled = 0
GuiConsoleVisible = 0

I also stopped any other built-in mod from loading, except for BPModLoaderMod, since that is what you need for mods to load. Changes are made in ue4ss\Mods\mods.txt - 0 means to not load, 1 means to load.
CheatManagerEnablerMod : 0
ConsoleCommandsMod : 0
ConsoleEnablerMod : 0
SplitScreenMod : 0
LineTraceMod : 0
BPML_GenericFunctions : 0
BPModLoaderMod : 1




; Built-in keybinds, do not move up!
Keybinds : 1

Installation
To install, download and unpack the archive and put the dwmapi.dll and ue4ss folder into YourSteamInstallLocation\steamapps\common\PROJECT QUARANTINE\Test_C\Binaries\Win64 folder. After that, refer to the installation manual of the mod you were installing.

Troubleshooting
If you launched the game with no BP mods, but with UE4SS installed and it crashed, launch it again. If it crashes again, launch it again. I'm not joking, during development of my first BP mod that would happen sometimes, just crashes for no reason. If it still crashes after two tries, message me (preferably on Discord - you can find it in my profile) and send the .dmp or .log files. To be fair, I probably won't be able to understand what is going on in there, but as they say in Russia, попытка не пытка.

And if it crashes with BP mods installed, try launching it without any mods and see if it works without them and then message whoever made the mod.

Turning UE4SS off
Simpliest way to turn it off I found is to rename the dwmapi.dll file - this way you won't need to delete or move anything. I just add a random letter at the start of the filename.