Failed to load Windows Mixed Reality Interop Library - UE 4.23

[scadl]

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?

[benew]

Yeah... I have exactly the same problem...

[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);

[benew]

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

[scadl]

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]

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]

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!

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

[uros.rajsic]

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!

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

[scadl]

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

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]

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]

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]

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

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]

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?

+1
Please, help us

[scadl]

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!

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?

+1
Please, help us

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.

---

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]

This issue still persists in 4.25.