Starting with v4.9 of 3D WebView for Android with Gecko Engine, Unity 2021.3.31 or newer is required. This is because new versions of the Mozilla GeckoView library require Java 11, and Unity 2021.3.31 is the first version of Unity capable of handling the Java 11 library thanks to its upgraded version of R8. If your project is targeting an older version of Unity, it's necessary to upgrade to 2021.3.31 or newer in order to use v4.9 or newer of 3D WebView for Android with Gecko Engine. If you wish to remain on an older version of Unity, you can do so by using 3D WebView v4.8 or older. Developers can download older versions of 3D WebView through the Vuplex Developer Dashboard.
Additional compatibility notes:
- Unity 2022.3: If your project uses Unity 2022.3, then 2022.3.38 or newer is required. This is because older versions of Unity 2022.3 have an issue where Unity creates too many thread local storage keys, which prevents Gecko from launching successfully (Bugzilla issue link, Unity issue tracker link).
- Unity 2023: Some older versions of Unity 2023 (< 2023.2.18) are also impacted by the thread local storage issue described in the point above. If you encounter an issue with Gecko crashing with Unity 2023, then please upgrade to Unity 2023.2.18 or newer.