Why is my MRTK Android AR App background black?

Question

I started a project on Unity version 2019.4.24f1, imported MRTK 2.6.1 foundation, tools, etc and set everything up according to this guide:

https://microsoft.github.io/MixedRealityToolkit-Unity/Documentation/CrossPlatform/UsingARFoundation.html

The App starts and shows the elements that I placed in the testscene (buttons, etc), but the background of the app is black and there is no camera access question from my android system.

The device I am testing on is a Oneplus 3T and the minumum SDK requirements are met. How can I get this to work? I will post my MRTK and Player Settings below:

MRTK Settings:

Player Settings:

XR Settings: (Note that If I activate AR Core tick, it displays an error)

Error when AR Core is ticked:

Packages:

Answer 1

So it turned out that my phone is just too old and doesn't support ARCore. The app worked on another phone just fine.

Answer 2

The screen is black is because the camera access is not granted.

Check if your manifest file has the camera access permission.

https://developer.android.com/guide/topics/manifest/uses-permission-element

Answer 3

If you follow the steps in this document to configure your project, but the Android device camera does not work with MRTK, it is recommended you double-check the following points:

1. Minimum API Level (Project Setting>Player>Android>Other Setting) should higher than Android 8.0.
2. After installing AR Foundation and ARCore XR Plugin packages, don’t forget to update the MRTK UnityAR scripting defines by invoking the menu item: Mixed Reality Toolkit > Utilities > UnityAR > Update Scripting Defines.
3. Make sure you have unchecked the ARCore Supported in the Legacy built-in XR support: Project Setting> Player>Android>XR Settings.
4. And then, nav to XR Plug-In Management and check the ARCore under the Android.
5. Vulkan Graphics API is not currently supported, please make sure to delete this and keep only OpenGLES3: Project Setting>Player>Android>Other Setting>Graphics APIs