Unreal Engine 4.20 Released!

please consider a future livestream covering the Digital Human Improvements .

this is a game changer !

Thank you for all of the new updates. The upgrade from 4.19 to 4.20 was a breeze <3

iOS Build with Plugin: Google VR enabled will STILL (Bug since 2017) Crash upon launcher on iOS Devices when On Shipping+Distribution…

i’m just waiting for this release T~T

Congratulations, but as per usual, the most important changes only get a footnote. :smiley: Let’s take a looksie…

That allocator thing is huge, I’m surprised it isn’t getting more love.

Edit - And of course this:

Just upgraded a project to 4.20 and now I get about 40 of these warning messages every time I open the project. Doesn’t happen on the 4.19 project.

Attempting to load an instance of a transient class from disk - Package:'../../../../../../Users/User/Documents/Unreal Projects/MyProject 4.20/Content/Maps/Test.umap'  Object:'EnvQueryManager_0'  Class:'/Script/AIModule.EnvQueryManager'

Any ideas?

I get this when running .\GenerateProjectFiles.bat -2017 :

PS E:\git\UnrealEngine> .\GenerateProjectFiles.bat -2017
Setting up Unreal Engine 4 project files...
Binding IntelliSense data... 0%E:\git\UnrealEngine\Engine\Plugins\Runtime
Display\Source\DisplayCluster\DisplayCluster.Build.cs: warning: Referenced directory 'E:\git\UnrealEngine\Engine\Plugins\Runtime
Display\ThirdParty\VRPN\Include' does not exist.
Writing project files... 100%

Is that ThirdParty directory something that Setup.bat should have pulled in? Setup.bat didn’t report any errors.


the directory did exist, but had a different capitalization. I was able to run GenerateProjectFile.bat without the warning by renaming E:\git\UnrealEngine\Engine\Plugins\Runtime
Display\ThirdParty\Vrpn to E:\git\UnrealEngine\Engine\Plugins\Runtime
Display\ThirdParty\VRPN .

For people running into it it seems to be either an issue with a windows update to WSL:

If you do a git checkout it seems to set a case sensitivity flag on any created folders now. This is only an issue if you are using WSL (Windows Subsystem for Linux) to do the git checkout. They have changed it to have this case sensitivity stuff by default all of the sudden.

solution is:

set /etc/wsl.conf to:


Awesome, a few more merge request I made were integrated in 4.20:

A few improvements to the Git Plugin:

And for more general Source Control Quality of life:

But also, in other area of the Editor:


Engine crashed at startup :frowning:

Access violation - code c0000005 (first/second chance not available)

UE4Editor_Engine!USkyLightComponent::UpdateSkyCaptureContentsArray() [d:\build\++ue4\sync\engine\source\runtime\engine\private\components\skylightcomponent.cpp:564]
UE4Editor_Engine!USkyLightComponent::UpdateSkyCaptureContents() [d:\build\++ue4\sync\engine\source\runtime\engine\private\components\skylightcomponent.cpp:632]
UE4Editor_UnrealEd!UEditorEngine::Tick() [d:\build\++ue4\sync\engine\source\editor\unrealed\private\editorengine.cpp:1619]
UE4Editor_UnrealEd!UUnrealEdEngine::Tick() [d:\build\++ue4\sync\engine\source\editor\unrealed\private\unrealedengine.cpp:403]
UE4Editor!FEngineLoop::Tick() [d:\build\++ue4\sync\engine\source\runtime\launch\private\launchengineloop.cpp:3495]
UE4Editor!GuardedMain() [d:\build\++ue4\sync\engine\source\runtime\launch\private\launch.cpp:166]
UE4Editor!GuardedMainWrapper() [d:\build\++ue4\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:144]
UE4Editor!WinMain() [d:\build\++ue4\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:223]
UE4Editor!__scrt_common_main_seh() [f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:283]

In this place:

Just trying out the new Proxy LOD. When generating Hierarchical LODs my CPU is only used about 8%.
Shouldn’t there be a higher CPU usage to generate the LODs faster?

i9 7980XE
GTX 1080 Ti

After another 30 minutes it’s still at 74%. It appears to be frozen. Thought this would be production-ready. Very disappointing.

I’m getting “…: Can’t find file for asset. /Script/EnvironmentQueryEditor” and my EQS queries are (logically) just Data Assets, but the EQSTester and BT tasks seem to work, and the EQS is out of the plugins list completely. Is it considered not experimental anymore, but the Query Editor got lost somewhere?

I didn’t really understant the purpose of this? Could you elaborate?

Do you mean hardware scalability?
Is it now possible to use the full power of two GTX 1080 ti in SLI mode? (FPS increase)

Is it my eyes or did you forget to mention Volume Texture Asset support in the release notes?

There are a lot of things missing… RichTextBlock is no longer experimental, a bunch of other more specific UMG widgets were added, new profiling tools/integrations, …

Hello, I tested the new node “Read Render Target Pixel” but it is very slow, it is possible that the node use too much access to the render target, it might be good to make another node that uses an array in input and output, this would allow to make a single access to the render target and to work only a variable without making several call.

Proposal of a new node: “Read render target pixel array”


  • Render Target 2D
  • 2D array int


  • array color RGBA

Single render target access, and single conversion to 2D texture.

Hello Kamrann,

I encountered this during the previews as well and asked ahead of time; This is intended. To avoid needing to use the full path, you can use the following format for your includes:

PublicIncludePaths.Add(Path.Combine(ModuleDirectory, “Public”));

-New: Curve Atlases in Materials
Does anyone else have a problem with “Curve Atlas Row Parameter” that is used in a material function that is used in another material function which is finally used in a material? Opening such material crashes the editor for me.

Yes, the fix for a curve atlas inside a material function crashing missed the 4.20 release, but it will be in the first hotfix. In the meantime, curve atlas row parameters should work in all cases except nested in a function.


Can you confirm that as of 4.20 you need High Sierra 10.13.5 minimum to run it on OSX?