forgive adlı üyeden alıntı: mesajı görüntüle
pubspec.yaml dosyasını neden paylaşmadınız?
https://stackoverflow.com/a/70335197/7880054
Burada diyor ki "Flutter'ı 2.8'e yükselttikten sonra bu hata ile karşılaştım çözümü ise flutter_math_fork: kütüphanesini ^0.5.0'e yükseltmek"
Siz de sanırım öyle bir şey yaptınız ya da Flutter 2.8 öncesinde çalışan kodu Flutter 2.8'de denediniz.
Çözüm
pubspec.yaml dosyasında şu satırı bu şekilde düzeltip yükseltmelisiniz.(öyle değilse)
flutter_math_fork: ^0.5.0
# https://developer.apple.com/library/...ationKeys.html
version: 1.0.0+2

environment:
sdk: ">=2.8.0 .0.0"

dependencies:
flutter:
sdk: flutter
scrollable_positioned_list: ^0.1.10
carousel_slider: ^3.0.0
flutter_rating_bar: ^4.0.0
smooth_page_indicator: ^0.2.3
video_player: ^2.1.6
http: ^0.13.3
chewie: ^1.2.0
better_player: ^0.0.72
seekbar: ^0.0.2
image_fade: ^0.2.1
url_launcher: ^6.0.6
font_awesome_flutter: ^9.1.0
cached_network_image: ^3.0.0
animated_text_kit: ^4.2.1
flutter_html: ^2.1.0
shared_preferences: ^2.0.6
retrofit: ^2.0.0
logger: 1.0.0 #for logging purpose
dio: ^4.0.0
firebase_core: ^1.4.0
google_sign_in: ^5.0.5
firebase_auth: ^3.0.1
flutter_facebook_auth: ^3.5.0
fluttertoast: ^7.1.6
need_resume: ^1.0.6
flutter_launcher_icons: "^0.9.2"

# The following adds the Cupertino Icons font to your application.
 # Use with the CupertinoIcons class for iOS style icons.
cupertino_icons: ^1.0.0

dev_dependencies:
flutter_test:
sdk: flutter
build_runner: any
change_app_package_name: ^1.0.0
flutter_icons:
android: true
ios: true
image_path: "assets/icon.png"
# 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
assets:
- assets/
- assets/images/
# 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: Oduda
fonts:
- asset: assets/fonts/Oduda.otf
# - 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