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jerostephan
New Participant
January 15, 2026
Question

Unity Compile Error: WindowsXRSimInstallationDetector not found

Hi there, I'm running into an interesting issue on Unity 6.3, using the 83 SDKs. I have installed the simulator, however in my Unity project I get compile errors (and subsequently can't use the simulator) as it seems the script doesn't  compile correctly. The following is the error:

 

Library\PackageCache\com.meta.xr.sdk.core@06273138c40d\Editor\MetaXRSimulator\XRSimInstallationDetector.cs(87,29): error CS0246: The type or namespace name 'WindowsXRSimInstallationDetector' could not be found (are you missing a using directive or an assembly reference?)

I've tried regenerating project files, reimporting assets and deleting the library folder, everything to no avail.

 

Would be great to get some help regarding this!

    10 replies

    jerostephanAuthor
    New Participant
    January 15, 2026

    This is happening on a clean Unity 6.3 project installing the All-In-One SDK.

    ChescoRed
    ChescoRed
    Inspiring
    January 15, 2026

    Same problem, even after updating the game while it's already running and with a clean install.

    The problem occurs with Unity version 6.3.4f1; there are no issues with Unity 6.3.3f1.

    VR Developer
      teawa
      Participant
      January 15, 2026

      Hey, any luck on this? Just updated my project and I'm having the same issue

        giadavigiano
        New Participant
        January 16, 2026

        I'm having the same issue

          Leoncitopc
          New Participant
          January 16, 2026

          I'm having the same issue. I eliminated the problem return to v81 

           

          NDimCube
          Meta Employee
          January 19, 2026

          Hi everyone,

          Thanks for your continued patience as we work through the Meta XR Core SDK v83 import issue in Unity 6000.3.4f1 LTS (and related versions). We want to share a clean workaround to keep your project structure and source control tidy while resolving this GUID collision:

          What’s causing the problem?

          • One .meta file in the SDK has a non-unique GUID, which can collide with other packages.
          • If you’re using a package manager, Unity will restore the original .meta and undo any manual fixes.

          How to work around this issue

          • Move the SDK package
            • Copy the entire Meta XR Core SDK v83 directory to somewhere outside your Unity project’s Assets—for example:
              /YourProject
/MetaXRCoreSDK
          • Reference the SDK locally
            • In your project’s Packages/manifest.json, set the SDK as a local package:
              {
  "dependencies": {
    "com.meta.xr.core": "file:../MetaXRCoreSDK"
  }
}
          • Remove the problematic .meta file
            • In the SDK directory (MetaXRCoreSDK), delete the problematic .meta file (e.g. WindowsXRSimInstallationDetector.cs.meta).
          • Regenerate the file
            • Open your Unity project again. Unity should automatically regenerate a new .meta file with a unique GUID.
          • Check that everything works
            • Confirm that the Meta XR Core SDK is imported without errors!

          ------------------------------------------------------

          This ensures your project stays organized and that the SDK doesn’t unexpectedly clutter your main repository or Assets folder.

          We know this isn’t ideal and are actively working on a permanent fix. If you need help on specific Unity versions or setups, please reach out!

          Thank you for your flexibility and let us know if you hit any snags with these steps.

            otoufman
            New Participant
            January 24, 2026

            Warning:

            if you do this, and if you're using not only core SDK ( like all-in-one or interaction SDK etc.), your project will collapse. Since other SDKs depend on core SDK, the way to move only the core SDK is so dangerous.

            I don't  understand why an employee writes a such shxt idea here. This doesn't solve our problems. NEVER do that again.

            PiteurMC
            Up and Coming
            January 20, 2026

            I downgraded to V81 and everything work fine for me now.


              stevesuddarth
              New Participant
              January 26, 2026

              How do you do the downgrade?  I couldn't find anything anywhere.

              otoufman
              New Participant
              January 24, 2026

              meta finally announced SDK Version 83.0.2 below, but there's no usable link.

              https://developers.meta.com/horizon/downloads/package/meta-xr-sdk-all-in-one-upm/

              since the unity asset store's version is not updated( it's still 83.0.1), there seems to be no way to download Version 83.0.2

              what NDimCube writes above sometimes works, but in my case it breaks all other my unity projects.

              v81 seems to be the only way, but some building blocks (like locomotion) do not appear on that version.

              could you please check the 83.0.2 download page ? I'm having the same trouble for almost around whole 1 week and so confused.

              To meta employees, this is the most important problem you have to solve for all developers. Why do you only release the release note and don't put the newest version in unity asset store...I'm so sad.

              As a conclusion, this problem still seems to be unsolved.

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