Android Studio 3.0 Beta 2 is now available in the Canary, Dev, and Beta channels.
This release fixes an issue which resulted in the compiler throwing a ClassNotFoundException when you enable Java 8 language features and specify minSdkVersion 19 or higher—this also caused some code analysis tools, such as ProGuard, to fail. For more information, see issue #64527520.
If you already have an Android Studio preview installed, you can get the update by clicking Help > Check for Update (or Android Studio > Check for Updates on Mac). Otherwise, you can download here.
Known issue: If you have an existing Android Studio project that's using an alpha version of Android plugin 3.0.0 (such as 3.0.0-alpha9), you may get the following error when you migrate to Android plugin 3.0.0-beta1 (or higher) and sync your project: Gradle project refresh failed.
Resolve this issue selecting Build > Clean Project from the menu bar—you need to perform this action only once for each project. You can then sync your project files with Gradle by clicking Sync Project from the toolbar.