Troubleshooting Guide: Fixing the 'Type or Namespace UnityEditor Not Found' Error in Unity

The 'Type or Namespace UnityEditor Not Found' error is a common issue faced by Unity developers. In this guide, we'll walk you through the steps to resolve this error, and answer some frequently asked questions about it. Follow the step-by-step instructions to have your project up and running in no time.

Table of Contents

• Prerequisites
• Step 1: Check Your Build Settings
• Step 2: Verify UnityEditor Namespace
• Step 3: Update Unity and Visual Studio
• Step 4: Reimport Your Assets
• FAQs

Prerequisites

Before we begin, make sure you have the following:

• Unity installed on your computer (Download here)
• Visual Studio or any other compatible C# IDE (Download here)
• A Unity project with scripts causing the 'Type or Namespace UnityEditor Not Found' error

Step 1: Check Your Build Settings

Check Platform

The UnityEditor namespace is only available when building for the Unity Editor. If you're trying to build for a different platform, such as iOS or Android, you'll encounter this error. To fix this, simply switch your build platform back to Unity Editor:

1. Open your Unity project
2. Go to File > Build Settings
3. Select PC, Mac & Linux Standalone

Conditional Compilation

If your script needs to work on both Unity Editor and other platforms, you'll need to use conditional compilation to exclude the UnityEditor namespace for non-editor builds.

Wrap the code that uses UnityEditor namespace with #if UNITY_EDITOR and #endif preprocessor directives:

#if UNITY_EDITOR
using UnityEditor;
#endif

...

#if UNITY_EDITOR
// Your code that uses UnityEditor namespace
#endif

Step 2: Verify UnityEditor Namespace

Check Spelling and Capitalization

Make sure you have typed the namespace correctly. C# is case-sensitive, so ensure the spelling and capitalization are correct:

using UnityEditor; // Correct
using Unityeditor; // Incorrect

Check Your References

Your script might be missing a reference to the UnityEditor.dll. To add the reference in Visual Studio:

1. Open your Unity project in Visual Studio
2. In the Solution Explorer, right-click References and select Add Reference
3. In the Assemblies tab, search for UnityEditor
4. Check the box next to UnityEditor and click OK

Step 3: Update Unity and Visual Studio

Outdated versions of Unity or Visual Studio might cause compatibility issues. Make sure both software are up-to-date:

• Update Unity: Open Unity Hub > Installs > Update or download the latest version from the Unity website
• Update Visual Studio: Open Visual Studio > Help > Check for Updates or download the latest version from the Visual Studio website

Step 4: Reimport Your Assets

If you've tried all the previous steps and the error persists, reimporting your assets might resolve the issue:

1. Open your Unity project
2. Go to Assets > Reimport All
3. Wait for Unity to finish reimporting assets
4. Check if the error is resolved

FAQs

1. What is the UnityEditor namespace used for?

The UnityEditor namespace provides access to classes and functions specific to the Unity Editor. It allows you to create custom editor scripts, tools, and extensions. Learn more about it in the Unity documentation.

2. Can I use UnityEditor in a build?

No, the UnityEditor namespace is not included in the final build of your project. It's only meant to be used in the Unity Editor. If you need to use UnityEditor functionality in a build, you'll need to find alternative solutions.

3. How do I create custom editor scripts?

Custom editor scripts are created using the UnityEditor namespace. You can find a comprehensive guide on creating custom editor scripts in the Unity documentation.

4. What are some common uses of the UnityEditor namespace?

Some common uses of the UnityEditor namespace include creating custom editor windows, modifying asset import settings, and creating custom inspectors for your scriptable objects. Learn more about these features in the Unity documentation.

5. Can I use the UnityEditor namespace in a script that is not an editor script?

Yes, you can use the UnityEditor namespace in any script, as long as it's being executed in the Unity Editor. However, remember to exclude the UnityEditor-specific code using conditional compilation when building for other platforms.

Related Links

• Unity Documentation: UnityEditor
• Unity Documentation: Custom Editor Scripts
• Unity Documentation: Conditional Compilation