Search Unity

Resolved DllNotFoundException (Error) when using SRanipal and Eye Tracking SDK

Discussion in 'VR' started by qttsc2021, May 1, 2022.

  1. qttsc2021


    Mar 29, 2022

    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
    aysegulbarlas likes this.
  2. aysegulbarlas


    Dec 30, 2017
    Hi, I have the exact same issue. Have you figured out the source of the problem?
  3. qttsc2021


    Mar 29, 2022
    Hi @aysegulbarlas

    So, I reached out to someone with Unity experience to visit my office and check the issue, and she managed to resolve the DLL error. She mentioned that the issue might be from a bug in the XR plugin when using OpenXR. So instead, I installed the SteamVR Plugin to my project.

    Please find the below summary of our troubleshooting session:


    Compatibility issue between OpenXR (Unity) and SRanipal SDK that causes the error "DllNotFoundException : Assets/ViveSR/Plugins/SRanipal.dll '' to appear.


    Uninstall XR from Unity and install SteamVR to use OpenVR instead of OpenXR.

    But at this stage of your project the above steps caused issues and errors.

    As a second plan I did the following:

    1- Created a new Project that uses URP.

    2- Installed SteamVR to this project.

    3- Imported SRanipal SDK to this project.

    4- Exported your project as a package and unchecked all the XR and the SRanipal SDK related folders.

    5- Imported the previous package to the new project.

    6- Because you were using a player that's provided from XR Interactions, I had to delete it too and replace it with "Player" prefab from SteamVR which has many more functionalities. For example : hand movements.

    7- Tested it and made sure everything was working as intended.