How to strip down Unreal GitHub Source

TOYSTORYLAB · September 2, 2025, 9:56am

Not sure whether this is the correct place to ask, but IMHO it seemed to be the most obvious place.

I had/have (as Launcher still does not work) quite an Odyssee the last days…
See this thread:

As Support only gave me standard solutions which I already have done,
such as
Clear the Epic Games Launcher cache
Run the Epic Games Launcher as an administrator
Reinstall the Epic Games Launcher
…

I decided to try to install Unreal Engine with GitHub Source.
As I am an animator/filmmaker, definitely not a tech nerd, this was quite challenging but I succeeded…
Now I have UE 5.6.1 installed, can connect to my huge assets library on Fab and add assets to my project.
So, at least I can start working again.

Cons:
Bloated Version 240 GB vs probably 50GB with Launcher.
In Launcher this installed version is not visible ;-/
As some of my assets have never been added to Fab, one sometimes need launcher to add these to project.
Unfortunately Launcher does not know where my created project is, so I can not use these assets.

So my questions are:
How do I strip the GitHub versions down so they don’t get that big?
There are so many things in it, I clearly don’t need.

And as I don’t want to make games, so I probably could strip it further down, even less than launcher version?

Any idea how to make sure launcher “sees” that UE “GitHub” version?

And where in the GitHub Folder would I direct my project so Launcher sees it so I can add assets from launcher (not Fab) to my project?

TOYSTORYLAB · September 2, 2025, 4:02pm

Hm, another limitation, I can not install Plugin from Launcher into engine ;-/

This is a huge limitation, so how does one install Plugins from Fab (apparently only possible via Launcher) into a UE GitHub Source version??

eray_ozr · September 2, 2025, 4:47pm

1- you can install your marketplace plugins. Look at Epic Launcher version Engine’s installation path. You will see Plugin/Marketplace like path. Everything is in there. To use them, create a project with source version of engine, create a folder with name “Plugins” copy plugins which you want.

2- There is no straightforward way to strip modules from source code.

3- Sometimes install button doesn’t work. For me problem was about plugin’s install button, not engine’s. But if you have this problem for very long time, you should consider to format your PC because problem can be anything. Currently I don’t have any problem about installing engine versions.

TOYSTORYLAB · September 2, 2025, 5:07pm

First of all, thanx for chiming in!

The problem is, I have no version of UE installed via launcher, so launcher thinks I have no UE installed…

And I need a plugin that should be installed in engine, not in project folder…

I just added a plugin that should be in project folder but when I launch that project I get notification that plugin should be built, and then second error, not possible…

Damned, I’m a filmmaker/animator, not a tech nerd!

zoe_wxq · September 2, 2025, 8:43pm

hi ,

you can delete the hidden folder (.git ) to save around 30Gb space.

you can clean and recompile the whole source code with disabling debug info (not generate .pdb files) to save huge space , almost like release version downloaded from EPIC Launcher , but after disabling debug info, all built Dlls should copy to a proper location (just like Launcher version) , otherwise you may not run unrealeditor.exe properly. (maybe there is a shell script for copying all built files to a proper location , but i haven’t found it yet….)

TOYSTORYLAB · September 2, 2025, 8:56pm

Thanx for chiming in!

I doubt I will be able to understand and execute what you wrote but I will check tomorrow as soon I am in the studio…

nande · September 2, 2025, 9:51pm

i think it could help to just make an “installed build” of the engine from your source build (it’s not that hard).

then you can throw away your source build. Installed Build Reference Guide for Unreal Engine | Unreal Engine 5.6 Documentation | Epic Developer Community

but please make sure your installed build covers your needs before deleting the source one.

TOYSTORYLAB · September 3, 2025, 8:33am

Thanx for chiming in…

I just checked that link and felt, well, overwhelmed

I doubt I can pull this off…

nande · September 3, 2025, 8:40am

Yeah it certainly looks overwhelming.

But if you successfully built a source version of the engine youre 90% there. All you ned to do is run one (or two ) commands. Look for the section thats actually named “moke installed build”

Im on wy phone so i cant give more details just now.

Good luck anyways.

TOYSTORYLAB · September 3, 2025, 8:42am

I’m just trying to make the needed lines…

TOYSTORYLAB · September 3, 2025, 8:57am

What I have now:

G:\EPIC\GIT_5.6.1\UnrealEngine-5.6.1-release\Engine\Build\BatchFiles\RunUAT.bat BuildGraph -target=“Make Installed Build Win64” -script=“Engine/Build/InstalledEngineBuild.xml” -clean

Hm, not sure where to put this:

-set:HostPlatformOnly=[true] (as I want Win64 only)

And would I need “DDC”?

Also not sure what to do with “Registering an Installed Build”…

TOYSTORYLAB · September 3, 2025, 10:21am

Hm, I asked Chat GPT…

This is what it gave me…

Any issues with this?

@echo off
REM -------------------------------
REM Settings
REM -------------------------------
set SOURCE_ROOT=G:\EPIC\GIT_5.6.1\UnrealEngine-5.6.1-release
set INSTALL_ROOT=G:\EPIC\UE_5.6.1_INSTALLED

REM -------------------------------
REM Step 1: Make Installed Build (Win64-only, no DDC)
REM -------------------------------
echo.
echo ===== Building Installed Build (Win64-only, no DDC) =====
“%SOURCE_ROOT%\Engine\Build\BatchFiles\RunUAT.bat” ^
BuildGraph ^
-target=“Make Installed Build Win64” ^
-script=“%SOURCE_ROOT%\Engine\Build\InstalledEngineBuild.xml” ^
-set:HostPlatformOnly=true ^
-set:WithDDC=false ^
-clean

if %ERRORLEVEL% neq 0 (
echo Build failed! Exiting.
pause
exit /b %ERRORLEVEL%
)

REM -------------------------------
REM Step 2: Copy to clean folder (excluding DDC)
REM -------------------------------
echo.
echo ===== Copying Installed Build to %INSTALL_ROOT% =====
if exist “%INSTALL_ROOT%” (
echo Existing folder found. Removing…
rmdir /s /q “%INSTALL_ROOT%”
)

xcopy “%SOURCE_ROOT%\Engine\Saved\Build\InstalledBuilds\Win64” “%INSTALL_ROOT%” /E /H /C /I

REM Remove any leftover DDC folder if it exists
if exist “%INSTALL_ROOT%\Engine\DerivedDataCache” (
echo Removing leftover DDC folder to save space…
rmdir /s /q “%INSTALL_ROOT%\Engine\DerivedDataCache”
)

if %ERRORLEVEL% neq 0 (
echo Copy failed! Exiting.
pause
exit /b %ERRORLEVEL%
)

REM -------------------------------
REM Step 3: Register Installed Build
REM -------------------------------
echo.
echo ===== Registering Installed Build =====
“%INSTALL_ROOT%\Engine\Binaries\Win64\UnrealVersionSelector.exe” /register

if %ERRORLEVEL% neq 0 (
echo Registration failed! Exiting.
pause
exit /b %ERRORLEVEL%
)

echo.
echo ===== Done! =====
echo Your UE 5.6.1 Installed Build is now in “%INSTALL_ROOT%” and registered with Epic Games Launcher.
pause

TOYSTORYLAB · September 3, 2025, 10:46pm

After a long day, with the help from Chat GPT, several failed attempts, AutomationTool errors, installing Windows 10 SDK with Debugging Tools, I finally have my “installed build” Thanx for pushing me in the right direction. Too tired to check launcher connection now, will be for tomorrow!

TOYSTORYLAB · September 3, 2025, 10:52pm

UE 5.6.1 GitHub → Installed Build Log (Day 1)

Starting point

Installed Unreal Engine 5.6.1 from GitHub Source.
Problem: Source folder = 240 GB, Launcher doesn’t see this build,
hard to use Marketplace/Fab assets.
Goal: Create a slim “Installed Build” so it works like the Launcher
version.

Preparation

Confirmed .NET SDK 9.0.304 installed.
Installed Windows 10/11 SDK with Debugging Tools → pdbcopy.exe found
in path.
Verified git version 2.51.0.windows.1.
Rebuilt AutomationTool with dotnet build to avoid warnings-as-errors
problem.

Installed Build attempt

Created .bat script to run
RunUAT.bat BuildGraph -target=“Make Installed Build Win64” …
First run failed due to missing pdbcopy.exe.
After SDK install, build ran 3+ hours and created content in
LocalBuilds\Engine\Windows.

Results

Found full build output here:
```
G:\EPIC\GIT_5.6.1\UnrealEngine-5.6.1-release\LocalBuilds\Engine\Windows
```
Containing:
- Engine\Binaries\Win64\UnrealEditor.exe
- FeaturePacks, Samples, Templates
Copied these into:
```
G:\EPIC\UE_5.6.1_INSTALLED
```
and verified UnrealEditor.exe runs.

Cleanup & Reorganization

Suggested moving to clean path for Launcher compatibility:
```
G:\EPIC\Engines\5.6.1
```
Copied everything there → confirmed UnrealEditor.exe works.
Plan to later remove:
- LocalBuilds folder (~75 GB).
- Entire GitHub source (~194–240 GB) after testing Launcher
  integration.

Next steps (tomorrow)

Register installed build so Epic Games Launcher detects UE 5.6.1 in
G:\EPIC\Engines\5.6.1.
Test whether Launcher can add Marketplace/Fab assets into projects
using this build.
Decide what can safely be deleted to reclaim disk space.

Current safe entry point:
G:\EPIC\Engines\5.6.1\Engine\Binaries\Win64\UnrealEditor.exe

nande · September 3, 2025, 10:59pm

sorry i wasn’t at the pc when you posted.

that missing pdb is a classic issue. there are posts in the forum here for that.

awesome work man! i don’t trust gpts, i usually rather search the forums or online, but im glad you made it work.

that summary seems good to me. thanks for sharing.

TOYSTORYLAB · September 4, 2025, 12:24pm

No problem…

Unfortunately Launcher does not recognize my build…

So I still can’t use assets that need launcher instead of Fab and I can not install plugins to engine ;-/

nande · September 4, 2025, 8:28pm

Ohh. I see.

I thought that by registering it, it would show up on the launcher.

You can try this one. I use it on linuk, it works on windows too.

If it doesnt detect the engine it can still dowload tte plugins.

But im sure it can detect the engines as it detects my source build.