DllNotFoundException: mediapipe_c | NullReferenceException: Object reference not set to an instance of an object

System information

• OS Platform and Distribution (e.g., Linux Ubuntu 20.04, WSL2): Windows
• Target (e.g. desktop cpu, android arm64): desktop cpu
• Bazel version: 4.1.0
• Python version: 3.7.8
• GCC/G++ version: 19.16.27045 for x64
• Unity version: 2020
• Android NDK version (if building for Android):
• Xcode version (if building for iOS):

Describe the problem Plugins: Failed to load ‘C:/Users/arham/Documents/extras/MediaPipeUnityPlugin/Packages/com.github.homuler.mediapipe/Runtime/Plugins/libmediapipe_c.dll’ because one or more of its dependencies could not be loaded.

Steps to reproduce the issue I tried to open in editor by clicking over DemoDesktop scene. Also tried to import it as package, Even I also reinstalled the Unity 2020.

Full logs

Plugins: Failed to load 'C:/Users/arham/Documents/extras/MediaPipeUnityPlugin/Packages/com.github.homuler.mediapipe/Runtime/Plugins/libmediapipe_c.dll' because one or more of its dependencies could not be loaded.
DllNotFoundException: mediapipe_c
Mediapipe.ResourceManager..ctor () (at Packages/com.github.homuler.mediapipe/Runtime/Scripts/Util/ResourceManager.cs:20)
Mediapipe.LocalAssetManager..ctor () (at <e2b237ecb26f4097b4aa4033f48ffa11>:0)
LocalAssetLoader.Start () (at Assets/Mediapipe/Samples/Scripts/ResourceManager/LocalAssetLoader.cs:5)
NullReferenceException: Object reference not set to an instance of an object
LocalAssetLoader.PrepareAsset (System.String name, System.String uniqueKey, System.Boolean overwrite) (at Assets/Mediapipe/Samples/Scripts/ResourceManager/LocalAssetLoader.cs:9)
DemoGraph.PrepareDependentAsset (System.String assetName, System.String uniqueKey, System.Boolean overwrite) (at Assets/Mediapipe/Samples/Scripts/DemoGraph.cs:192)
DemoGraph.PrepareDependentAsset (System.String assetName, System.Boolean overwrite) (at Assets/Mediapipe/Samples/Scripts/DemoGraph.cs:196)
FaceDetectionGraph.PrepareDependentAssets () (at Assets/Mediapipe/Samples/Graphs/FaceDetection/Scripts/FaceDetectionGraph.cs:57)
DemoGraph.Initialize () (at Assets/Mediapipe/Samples/Scripts/DemoGraph.cs:46)
SceneDirector+<RunGraph>d__23.MoveNext () (at Assets/Mediapipe/Samples/Scripts/SceneDirector.cs:171)
UnityEngine.SetupCoroutine.InvokeMoveNext (System.Collections.IEnumerator enumerator, System.IntPtr returnValueAddress) (at <e414e10bfe5f45729ff122f3359de21b>:0)

Additional context Even I ignore this DLL error and run the scene but it is producing following error:

NullReferenceException: Object reference not set to an instance of an object
LocalAssetLoader.PrepareAsset (System.String name, System.String uniqueKey, System.Boolean overwrite) (at Assets/Mediapipe/Samples/Scripts/ResourceManager/LocalAssetLoader.cs:9)
DemoGraph.PrepareDependentAsset (System.String assetName, System.String uniqueKey, System.Boolean overwrite) (at Assets/Mediapipe/Samples/Scripts/DemoGraph.cs:192)
DemoGraph.PrepareDependentAsset (System.String assetName, System.Boolean overwrite) (at Assets/Mediapipe/Samples/Scripts/DemoGraph.cs:196)
FaceDetectionGraph.PrepareDependentAssets () (at Assets/Mediapipe/Samples/Graphs/FaceDetection/Scripts/FaceDetectionGraph.cs:57)
DemoGraph.Initialize () (at Assets/Mediapipe/Samples/Scripts/DemoGraph.cs:46)
SceneDirector+<RunGraph>d__23.MoveNext () (at Assets/Mediapipe/Samples/Scripts/SceneDirector.cs:171)
UnityEngine.SetupCoroutine.InvokeMoveNext (System.Collections.IEnumerator enumerator, System.IntPtr returnValueAddress) (at <e414e10bfe5f45729ff122f3359de21b>:0)

[homuler]

It usually occurs when you start Unity before building native libraries (Unity removes .meta files). cf. https://github.com/homuler/MediaPipeUnityPlugin/issues/186#issuecomment-851253589

Even after setting “Load on startup” the error comes back when i restart unity.

On Windows, please just ignore this error if it works. It seems that libmediapipe_c.dll must be loaded after OpenCV but we cannot specify the order.

[Arham-Aalam]

Thanks @homuler it worked, In my case I was using OpenCV 3.4.15 So my DLL file was opencv_world3415.dll but the meta file was opencv_world3410.dll.meta, So instead of changing my OpenCV version I try to rename meta as opencv_world3415.dll.meta and it worked! Also don’t forget to enable “Load on startup” for opencv DLL file.