ARCore SDK console error: `SpatialTracking' does not exist in the namespace ÚnityEngine'

Just following the instructions from the google developers website to get ARCore running in Unity leads to this console error:
Assets/GoogleARCore/SDK/InstantPreview/Scripts/InstantPreviewManager.cs(32,23): error CS0234: The type or namespace name `SpatialTracking' does not exist in the namespace `UnityEngine'. Are you missing an assembly reference?

And furthermore I have: Assets/GoogleARCore/Examples/CloudAnchor/Scripts/ARKitHelper.cs(50,71): error CS0246: The type or namespace name `Pose' could not be found. Are you missing an assembly reference?

I couldn't find anything online relating to this error, and would appreciate any help.

Thanks

 

Solved, was running on older Unity version.

 

May I know which Unity version you are using to solve this issue?

 

I have the same issue with Unity3D 2019.1.1f1
ARCore package I have imported is: arcore-unity-sdk-v1.9.0.unitypackage

 

Make sure you enable the appropriate packages that our samples use. See https://developers.google.com/ar/develop/unity/enable-arcore, specifically the "Unity 2019" section.

 

I still have this problem on Unity 2019.1.3f1

TrackedPoseDriver.cs exists in my project.

it reads

Code (CSharp):

1. [assembly: InternalsVisibleTo("UnityEditor.SpatialTracking")]

then below

Code (CSharp):

1. namespace UnityEngine.SpatialTracking

could this be a mismatch?

 

I just ran into this issue during package maintenance:

As Chaosemer points out, the solution is clearly stated on the ARCore website. (Which ideally should be split by Unity version given that each version has its required tweaks)

Download the ARCore SDK for Unity and import it into your project by clicking the menu Assets > Import package > Custom Package. (Unity 2019 only: To fix the compilation errors, use Window > Package Manager to install the Multiplayer HLAPI and XR Legacy Input Helpers packages.)

https://developers.google.com/ar/develop/unity/enable-arcore

 

You're amazing with that unity 2019 only piece of information!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!