How do I upgrade an existing flutter app?

With Dart:

First, comment that the packaging line in the pubspec. yaml file and run flutter pub get after successfully get packages to uncomment that line (if you want to upgrade/downgrade to a specific version that mentioned version too) it will upgrade to the latest version.

To upgrade to a new version of the package, for example to use new features in that package, run flutter pub upgrade (Upgrade dependencies in IntelliJ or Android Studio) to retrieve the highest available version of the package that is allowed by the version constraint specified in pubspec. yaml .