MARS_Installer.unitypackage does not load on Unity LTS 2021.3.1f1

Unity Engine
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1

I’ve tried many separate times to install Unity MARS starting with a blank project and each time I run into errors. Here are two methods I’ve tried-

  • Starting with a completely blank project opening MARS_Installer.unitypackage creates a blank folder called MARS under Assets. I get a number of messages in the console that packages were installed successfully. I see a new MARS tab in the top bar but the only options there are AutoInstall > Ensure MARS installed and AutoInstall > Check MARS Auto Installed. Neither of those options do anything. There is no MARS context menu under Window. I get the following error in the console:

  • Library\PackageCache\com.unity.jobs@0.2.9-preview.15\Unity.Jobs\IJobParallelForDefer.cs(73,85): error CS8377: The type ‘U’ must be a non-nullable value type, along with all fields at any level of nesting, in order to use it as parameter ‘T’ in the generic type or method ‘NativeList’

  • Starting with a completely blank project if I install AR Foundation, ARCore XR Plugin and ARKIT XR Plugin the MARS_Installer.unitypackage creates a MARS folder in Assets with 5 installer files. From this folder there is no option to complete the installation. There is no MARS tab in the top bar. There is no MARS context menu under Window. The console gives 4 errors:

  • [Package Manager Window] Cannot perform upm operation: Package [com.unity.labs.mars-auto-installer] cannot be found [NotFound].
    UnityEditor.EditorApplication:Internal_CallUpdateFunctions ()

  • [Package Manager Window] Cannot perform upm operation: Unable to add package [com.unity.labs.mars-auto-installer]:
    Package [com.unity.labs.mars-auto-installer] cannot be found [NotFound].
    UnityEditor.EditorApplication:Internal_CallUpdateFunctions ()

  • [Package Manager Window] Error adding package: com.unity.labs.mars-auto-installer.
    UnityEditor.EditorApplication:Internal_CallUpdateFunctions ()

  • Library\PackageCache\com.unity.jobs@0.2.9-preview.15\Unity.Jobs\IJobParallelForDefer.cs(73,85): error CS8377: The type ‘U’ must be a non-nullable value type, along with all fields at any level of nesting, in order to use it as parameter ‘T’ in the generic type or method ‘NativeList’

Any ideas how I can get this working? I’m on a 45 day trial and I’m trying to not waste time on just the install. I’ve sent a ticket in to Unity Support and haven’t received a response yet.

2

Hi there! Sorry to hear you’re having trouble. We just became aware of an issue with the ar-companion-core package and its dependencies in 2021.3.1f1 and above, which you just hit. The issue is not present in 2021.3.0f1, so if you are able to roll back one patch version, that should work.

You should also be able to install MARS “manually” but adding it to your package manifest. All you need to do is add the following lines to your package manifest:

"com.unity.mars": "1.4.1",
"com.unity.mars-ar-foundation-providers": "1.4.1",
"com.unity.mars-nav-mesh": "1.4.1",

If you need the companion app package, I was able to get it to work earlier by manually adding the correct dependency versions to the project manifest. Adding this set of packages worked for me:

"com.unity.ar-companion-core": "1.0.1-preview.2",
"com.unity.runtime-scene-serialization": "0.3.4-preview",
"com.unity.serialization": "1.5.0-preview",
"com.unity.jobs": "0.2.9-preview.15",
"com.unity.collections": "0.8.0-preview.5",

We’re working on resolving this issue for future customers. The current version of the MARS installer (updated a this afternoon) will leave off the AR companion package in 2021.3, but we should be able to push some new package versions very soon which work without this workaround. Thank you for your patience. I’ll update this thread when the issue is resolved.

3

Hello again.

As of a few minutes ago, the MARS Installer was updated to work in 2021.3. It will now explicitly install com.unity.runtime-scene-serialization@0.6.0-preview along with the AR Companion package, which is compatible with Unity 2020.3 and above. Crucially, it uses a version of com.unity.properties and com.unity.collections which is upgradable, so nothing breaks when 2021.3.1f1 overrides the version of Collections.

Long story short, if you download and use the latest installer or just add the following package to your project manifest, you should be good to go:

"com.unity.runtime-scene-serialization": "0.6.0-preview"
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4

Thank you! The new installer worked.

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