The type or namespace name 'Newtonsoft' could not be found

Issue

After importing AI Dev Kit into Unity, you encounter a flood of errors saying &#xNAN;“The type or namespace name 'Newtonsoft' could not be found.” like in the screenshot below.

Possible Cause

In rare cases, Unity fails to automatically apply the required Scripting Define Symbol (UNITY_NEWTONSOFT_JSON, CYSHARP_UNITASK) during installation. This prevents the editor scripts from activating, resulting in the AI Dev Kit menu not appearing.

How to Fix

• Open File > Build Settings > Project Settings > Player > Other Settings

• Locate the Scripting Define Symbols field for your current build target

• Manually add these two symbols:

  UNITY_NEWTONSOFT_JSON
  CYSHARP_UNITASK

• Press Enter or click elsewhere to confirm the change

• Unity should now recompile the scripts, and the AI Dev Kit menu should appear under Tools

If It Still Doesn’t Work

• Sometimes, Unity also fails to automatically install required dependencies during the package import. Make sure you have following folders in Packages in your project window:

  • Newtonsoft Json

  • UniTask

• If you are missing any of the above, manual install the dependencies.

  • Newtonsoft.Json: Manual Installation Guide

  • Cysharp.UniTask: Manual Installation Guide

• Each guide provides step-by-step instructions for adding the packages to your Unity project and verifying that everything is set up correctly. After completing the installations, restart Unity to ensure the changes take effect.

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