Capacitor 4.0 has been released, bringing numerous bug fixes, codebase improvements, and updates to support new Google Play policies, while maintaining ease of migration from previous versions. The upgrade from Capacitor 3.0 is designed to be straightforward, requiring minimal changes to existing codebases due to the solid foundation established in version 3. Developers can follow a detailed migration guide available in the documentation and utilize tools like the Capacitor CLI or the Ionic Extension for Visual Studio Code for a seamless transition. Additionally, changes have been made to some plugins, so reviewing the migration documentation is recommended for a smooth update process.