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DllNotFoundException (Error) when using SRanipal and Eye Tracking SDK

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I am a researcher at a university that is designing a VR experiment (using HTC Vive Pro Eye). I am using VIVE Eye and Facial Tracking SDK and SRanipal Runtime ( to collect Eye Data, however, I keep on receiving an error (please find attached). Can anyone please help me on how I can resolve this issue? Thank you.

Eye Tracking Error.PNG

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The Unity Editor Version I used is 2020.3.32f1.

And the sample scene I launched is EyeSample_v2

I did not have this issue in the past, it only started when I opened a project online that provided a programming code to extract eye data: Motor Control and Learning · GitHub

The research paper that provided this code is attached for your reference.


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Hi @Justine,

I might need time to check what is happening after you includes SaccadeVR-mobile together with SRanipal SDK.

Just to double check your setup environment,

1. Unity Editor 2020.3.32f1

2. VIVE Eye and Facial Tracking SDK

3. SRanipal Runtime (

4. SaccadeVR-mobile

Is that correct?

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Yes that is all correct.

In addition, when I click on the "missing" Dll/Plugin, I see a warning message in the inspector saying "Once a native plugin is loaded from script, it's never unloaded. If you deselect a native plugin and it's already loaded, please restart Unity". Maybe this has something related to the issue? Kindly find attached image for your reference.

Thank you so much for your reply and I hope to hear back from you soon! 🙂

Eye Tracking Error 2.PNG

Edited by Justine
Forgot to attach image
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