> For the complete documentation index, see [llms.txt](https://aatkit.gitbook.io/aatkit-unity-integration/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://aatkit.gitbook.io/aatkit-unity-integration/other/unity-2019.3.x-potential-issue.md).

# Unity 2019.3.X Potential Issue

Resolve building issues with some Unity 2019.3.X versions

If there is `mainTemplate.gradle` file in your project and you use Unity 2019.3.X there might be building errors like:

```gradle
java.lang.RuntimeException: Duplicate class android.support.customtabs.ICustomTabsCallback found in modules classes.jar (androidx.browser:browser:1.0.0) and classes.jar (com.android.support:customtabs:26.1.0)

UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr) (at /Users/builduser/buildslave/unity/build/Modules/IMGUI/GUIUtility.cs:187)
```

To resolve it, please create settingsTemplate.gradle in project’s `Assets/Plugins/Android` directory. Add this code to the new file:

```gradle
gradle.rootProject {
    it.afterEvaluate {
        it.allprojects {
            // Since Unity 2019.3 enabling Jetifier via mainTemplate.gradle is no longer working
            it.ext['android.useAndroidX'] = true
            it.ext['android.enableJetifier'] = true
        }
    }
}

include ':launcher', ':unityLibrary'
**INCLUDES**
```