Failed to load Windows Mixed Reality Interop Library - UE 4.23

scadl · September 13, 2019, 5:15pm

Hello. I getting this error, while running my packaged game. I’m packaging with Win64 target.
I used same setting on UE 4.22.3 GitHub, and packaged my game, which running without any errors.

I tried to rebuild the MixedRealtityInterop plugin (from Engine/Source/Plugins/ThirdParty) – didn’t help.
I tried to install binary version of UE 4.23.0 (Epic Launcher) – same problem there.

So, where should I look?

anonymous_user_6b881482 · September 17, 2019, 9:15am

Yeah… I have exactly the same problem…

ItsNotMeTrustMe · September 17, 2019, 11:51pm

Had this same problem. I got it working again by copying a few lines from the 4.22 branch into 4.23. In ‘WindowsMixedRealityHMD.cpp’, you’ll see a comment “// Then finally try to load the WMR Interop Library” and the error message is right after that. Before that comment, around line 174, add this:


FString PerceptionSimulationDLLPath = EngineDir / "Binaries" / BinariesSubDir / "Microsoft.Perception.Simulation.dll";
FString HolographicStreamerDesktopDLLPath = EngineDir / "Binaries" / BinariesSubDir / "HolographicStreamerDesktop.dll";

void* PerceptionSimulationDLLHandle = FPlatformProcess::GetDllHandle(*PerceptionSimulationDLLPath);
void* HolographicStreamerDesktopDLLHandle = FPlatformProcess::GetDllHandle(*HolographicStreamerDesktopDLLPath);

anonymous_user_6b881482 · September 18, 2019, 3:37pm

Thanks for reply!
Hmm I think will wait for fix in Launcher Version…

scadl · September 18, 2019, 3:48pm

ItsNotMeTrustMe:

Had this same problem. I got it working again by copying a few lines from the 4.22 branch into 4.23. In ‘WindowsMixedRealityHMD.cpp’, you’ll see a comment “// Then finally try to load the WMR Interop Library” and the error message is right after that. Before that comment, around line 174, add this:
FString PerceptionSimulationDLLPath = EngineDir / "Binaries" / BinariesSubDir / "Microsoft.Perception.Simulation.dll";
FString HolographicStreamerDesktopDLLPath = EngineDir / "Binaries" / BinariesSubDir / "HolographicStreamerDesktop.dll";

void* PerceptionSimulationDLLHandle = FPlatformProcess::GetDllHandle(*PerceptionSimulationDLLPath);
void* HolographicStreamerDesktopDLLHandle = FPlatformProcess::GetDllHandle(*HolographicStreamerDesktopDLLPath);

And I CONFIRM that this solution really works for me! So **ItsNotMeTrustMe, **you saved my day, and not only one!
To everyone, who will use this, I strongly recommend to rebuilt MixedRealtityInterop plugin before repacking your game!

User-970075953 · September 24, 2019, 8:34am

ItsNotMeTrustMe:

Had this same problem. I got it working again by copying a few lines from the 4.22 branch into 4.23. In ‘WindowsMixedRealityHMD.cpp’, you’ll see a comment “// Then finally try to load the WMR Interop Library” and the error message is right after that. Before that comment, around line 174, add this:
FString PerceptionSimulationDLLPath = EngineDir / "Binaries" / BinariesSubDir / "Microsoft.Perception.Simulation.dll";
FString HolographicStreamerDesktopDLLPath = EngineDir / "Binaries" / BinariesSubDir / "HolographicStreamerDesktop.dll";

void* PerceptionSimulationDLLHandle = FPlatformProcess::GetDllHandle(*PerceptionSimulationDLLPath);
void* HolographicStreamerDesktopDLLHandle = FPlatformProcess::GetDllHandle(*HolographicStreamerDesktopDLLPath);

Thanks for posting this - saved me some time debugging it. Should really have been picked up in QA as it seems any use of the WMR plugin in a build will fail.

urosrajsic · October 4, 2019, 2:35pm

how do you rebuild the plugin? do you rebuild the whole engine from source?

uros.rajsic · October 4, 2019, 2:39pm

how do you rebuild individual plugins? do you need to rebuild the whole engine from source?

scadl · October 4, 2019, 7:04pm

The plugins has their own solution, which I recommend rebuilt before trying to build (not rebuild) the engine itself. In our case the SLN of WMR is here: <UE folder>\Engine\Source\ThirdParty\WindowsMixedRealityInterop

InceptTn · October 7, 2019, 2:45pm

Thank you for guys for solving this (important) issue for WMR developers. It seems that the late Hololens 2 implementation messed up the UE-71625 commit (https://github.com/EpicGames/UnrealE…10e6cff7b89030).

@scadl could you please elaborate on how you rebuild the WMR plugin? I am receiving an error when using the “RunUAT.bat” batch file to rebuild the plugin “<UE folder>\Engine\Plugins\Runtime\WindowsMixedReality\WindowsMixedReality.uplugin”.

Edit: To whom it may concern, I had to build the release version of Unreal (from github) to change the WMR plugin and build the whole project. I confirm that this solution works. Cheers!

User-970075953 · November 14, 2019, 9:18pm

This is still an issue in the 4.24 branch. Can confirm that the code deletion in 4.23 breaks the WMR plugin and that the fix above corrects it.

SharpasaBlade · November 19, 2019, 6:24pm

Having the same exact problem, added the lines in the .cpp, now I have no idea how to rebuild this WindowsMixedRealityInterop.Build… Can anyone specify what exactly needs to be done or at least llink me any guide on this?

arthew0 · November 21, 2019, 10:34pm

+1
Please, help us

scadl · November 21, 2019, 11:57pm

The only thing I did, I opened the solution of this plugin (MixedRealityInterop.sln).
And (Re)Builded the same way you do this with the Engine itself.

There are two projects inside, one for HoloLens and one for WMR.
I also noticed there are only two target architectures: Arm64, win64.
[HR][/HR]
In the launcher (prebuilt) version of UE you don’t have this SLN,
So I just generated poject source, modified plugin, and repackaged it.
I think this is less reliable way to fix this, because now I have problems with height detection…
Sorry, I couldn’t find the way to fix this on current launcher version of UE 4.23.1
As a temporal solution, I switched to OpenXR plugin and enabled in Mixed Reality Portal

Motanum · July 17, 2020, 3:25pm

This issue still persists in 4.25.

Rockam · July 28, 2020, 1:04pm

Does someone knows how to fix this on UE4.24.3? All those lines changed so much, and the error persists.

scadl · July 31, 2020, 7:12am

Sorry, I couldn’t find a way to apply discussed sources patch to 4.23.1, 4.24.0+, 4.25.0+. It really seamed that Epic just dropped WMR support.

My solution - is to use OpenXR plugin as replacement, while having it turned on in Windows Mixed Reality Portal.
It works pretty good and stable, with all VR headset settings and sensors, but have very wack key mapping, so I trying to figure out what is what.

Rockam · August 1, 2020, 8:36am

Ou, then I will try the OpenXR plugin by the moment, thank you so much!!