Unreal Engine 5.1 Preview

I am looking for the persist changes in multiuser server. Anyone found this?

I’ve been seeing this issue with a number of things using Nanite in 5.1. None of the settings on the meshes really do anything that I could see. This is using the “Modular Scifi Season 2 Starter Bundle” off the marketplace but it does apply to a lot of other meshes. It’s a new project just enabling Nanite on the meshes.

I’m using an RX 6800 XT with 22.10.1 drivers on W10. The same thing happens with an RX 480.

r.Nanite.ProgrammableRaster 0 is the only thing that seems to make these issues with missing geometry go away which I guess is closer to 5.0 functionality.

Thanks for the clarification, however I do not understand how a shader code which has 2 or 3 times the amount of instructions of its predecessor could be as efficient. Any light shed on this would be appreciated.


[EDIT: reply accidentally got duplicated, deleting one]

The instructions used to derive the count are abstract, they are not direct GPU hardware instructions (which are different for every GPU vendor). They are referred to as an “intermediate language” (IL). The IL is converted to GPU instructions by the graphics driver at a later stage. The final GPU instructions should be roughly the same whether from SM5 or SM6, but the IL for SM6 is completely different. It is documented here if you are curious.


I started having problems with MetaSounds in this version. Although it works perfectly fine in the editor and debugging the game/simulation. But when cooking and packaging, the generated executable does not start.

Opening with the -log parameter, the last log call is:

[2022.10.30-19.04.21:268][  0]LogMetaSound: Error: Target interface is not registered [InterfaceVersion:UE.Source.OneShot v1.0]
[2022.10.30-19.04.21:271][  0]LogMetaSound: Error: Target interface is not registered [InterfaceVersion:UE.Source v1.1]
[2022.10.30-19.04.21:271][  0]LogMetaSound: Error: Target interface is not registered [InterfaceVersion:UE.OutputFormat.Stereo v1.0]

After these calls in the log, the executable freezes with a black screen.

I saw a similar issue that was already fixed in Unreal 5.0: Unreal Engine Issues and Bug Tracker (UE-150434)

In my case, I was also using FObjectFinder, so after seeing this link, I chose to declare a UPROPERTY and assign the value via Blueprint, but it didn’t solve the problem. In the project where I’m having this problem, I’m using MetaSounds in a Modular Feature/Plugin (via Game Features & Modular Plugins)

Also tried setting the plugin (in this case, changed my plugins - Metasounds is declared as PreDefault) Loading Phase to PostDefault, but did not change the result.

  • Note 1: I’m packaging the project for Win64 and this was not happening in Unreal 5.0 (I understand that it is not recommended for shipping projects built in this preview, my project is not a finished game and will not be distributed. I’m packaging to perform more tests outside the development environment)

  • Note 2: This project was converted from Unreal 5.0 to 5.1 P1 and then to 5.1 P2.

Anyone else having problems with UUserWidget::SetPositionInViewport()?
With 5.0.3 my drag-drop widgets (based on the official tutorial Creating Drag and Drop UI | Unreal Engine Documentation ) worked perfectly fine, now they are all stuck at position {0,0} (top left) and SetPositionInViewport() does not change anything, despite getting the correct position input values.

It seems they added a new subsystem for handling widgets (UGameViewportSubsystem), perhaps it’s not working correctly yet?

Do you have any updates regarding Nanite in Linux and macOS? :slight_smile:

There is no workaround that I am aware of. I also don’t know if this is intended or a bug since I can’t seem to get a response to that from Epic. :frowning:

I haven’t been able to find someone with the same problem here, so I’m asking:
I can’t open version 5.1 preview 2.
The initiator starts up but closed when it reaches the moment of opening, this happens every time. Version 5.1 preview 1 could be opened without any problem and it worked perfectly.

Does this happen to someone? Any suggestion?

PD: Ok, solved,update Quixel Bridge plugin

I don’t know if it’s reported but when I “CopyPaste” elements from a project to another, UE 5.1 PV2 Crash.

Hope this helps.

A 5.0.3 Project with simple DMX faders does not work when upgraded to 5.1. Any insights?

I have a simple project that fades DMX channel 1 up and down. The project functions as expected in 5.03, but not 5.1 preview 2.

Has anyone tested compiling the 5.1 branch in an M1 Max with MacOS 13.0 Ventura and Xcode 14?
I am giving this a try to see if at least I can get the editor and the compiler to work (broken after upgrade to Ventura :-1 )

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I am also having gross artifacting on my M1 Studio Max under UE 5.1.0-22491701
Here’s a demonstration:

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The same for me on Mac Studio. It worked with 5.1 preview 1, but now it’s broken with preview 2.

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Apparently, if you disable fast math optimizations in the project settings, this goes away. However, it needs to rebuild.


Possible bug in 5.1 preview 2: everytime I “Reimport base mesh” from the Mesh viewer, a new material slot is being added. I import as Nanite mesh.

Possible bug in 5.1 preview 2: in texture editor with a 16 bits png texture grayscale used for displacement, changing the compression settings to “Displacementmap (GB/16)” makes the texture display all red. The texture is properly handled though (like for modeling tool’s displacement) but we cannot visualize it properly in the texture view.

Bug in 5.1 preview 2: using LightWeight Mesh Instancing (plugin), sometimes meshes disappear from level as they are converted to LWI (even when restarting the editor). LWI is an amazing feature, I’d love to see it fully operational in 5.1 release, it doesn’t seem there is a lot of work left to have it working.

Edit: problem is not always reproducible, I had a case where the meshes would not disappear. Not sure yet what is causing/not causing it.

Other issues I’ve found:

  • Convert 2 meshes into LWI, then select each of them and change their transform properties: sometimes the transform properties apply to the other instance instead of the one selected. When this happens, when selecting an instance, the gizmo jumps to the other instance(!).

  • END key doesn’t place instances on the ground as this is the case with regular static meshes.

yes, that same for me, I’m calling Widget->SetPositionInViewport from c++, and the Widget always stays at (0,0)