Upgraded to Flutter 3.0 from 2.8.1, getting: Warning: Operand of null-aware operation '?.' has type 'PaintingBinding' which excludes null error

Question

Upgraded to Flutter 3.0 from 2.8.1, getting: Warning: Operand of null-aware operation '?.' has type 'PaintingBinding' which excludes null error

It's on binding.dart - a file I don't touch at all.

() => PaintingBinding.instance?.imageCache?.evict(key),
                            ^

Any chance you guys know how I can fix it?

Don't know if related, but also seeing this a lot:

Class 'kotlin.Unit' was compiled with an incompatible version

Used the guide here to migrate: https://github.com/flutter/flutter/wiki/Upgrading-pre-1.12-Android-projects

This is my pubspec:

environment:
  sdk: '>=2.12.0 <3.0.0'

dependencies:
  flutter:
    sdk: flutter
  flutter_localizations:
    sdk: flutter

  google_maps_flutter: ^2.0.6
  rxdart:
  shimmer:
  cupertino_icons: ^1.0.3

  dependencies:
  flutter_svg: ^1.0.0

  http: ^0.13.3
  flutter_spinkit: ^5.0.0
  url_launcher: ^6.0.9
  html: ^0.15.0
  cached_network_image: ^3.1.0
  collection: ^1.15.0
  share_plus: ^3.0.4
  flutter_native_splash: ^1.3.2


dev_dependencies:
  flutter_test:
    sdk: flutter
  flutter_launcher_icons: ^0.9.2

flutter_icons:
  android: true
  ios: true
  image_path: "assets/app/launch/ic_launcher.png"
  adaptive_icon_padding: true

# For information on the generic Dart part of this file, see the
# following page: https://dart.dev/tools/pub/pubspec

# The following section is specific to Flutter.
flutter:

  # The following line ensures that the Material Icons font is
  # included with your application, so that you can use the icons in
  # the material Icons class.
  uses-material-design: true

  # To add assets to your application, add an assets section, like this:
  # assets:
  #  - images/a_dot_burr.jpeg
  #  - images/a_dot_ham.jpeg

  # An image asset can refer to one or more resolution-specific "variants", see
  # https://flutter.dev/assets-and-images/#resolution-aware.

  # For details regarding adding assets from package dependencies, see
  # https://flutter.dev/assets-and-images/#from-packages

  # To add custom fonts to your application, add a fonts section here,
  # in this "flutter" section. Each entry in this list should have a
  # "family" key with the font family name, and a "fonts" key with a
  # list giving the asset and other descriptors for the font. For
  # example:
  # fonts:
  #   - family: Schyler
  #     fonts:
  #       - asset: fonts/Schyler-Regular.ttf
  #       - asset: fonts/Schyler-Italic.ttf
  #         style: italic
  #   - family: Trajan Pro
  #     fonts:
  #       - asset: fonts/TrajanPro.ttf
  #       - asset: fonts/TrajanPro_Bold.ttf
  #         weight: 700
  #
  # For details regarding fonts from package dependencies,
  # see https://flutter.dev/custom-fonts/#from-packages

Answer 1

So, something which helped me:

1. remove the next folder /Users/your-user/.pub-cache/hosted/pub.dartlang.org
2. hit flutter pub upgrade

and then try to run your project ?

Answer 2

For the ones that have the same issue: changing my Kotlin version (manually), did the trick.

Now, in build.gradle:

buildscript {
    ext.kotlin_version = '1.6.21'
    repositories {
        google()
        jcenter()
    }

I have this instead of version 1.3.40

Answer 3

remove "?" at () => PaintingBinding.instance?.imageCache?.evict(key),