Flutter-升级Try removing the packa

1. 升级flutter出了问题

【Try removing the package language version or setting the language version to 2.10 or higher.】

dart "/Users/gitartos/Desktop/flutter_projects/flutter_app/lib/main.dart"
flutter_app/lib/main.dart: Warning: Interpreting this as package URI, 'package:flutterapp/main.dart'.
../../opt/flutter/packages/flutter/lib/src/material/about.dart:123:8: Error: Null safety features are disabled for this library.
Try removing the package language version or setting the language version to 2.10 or higher.
    Key? key,
       ^
../../opt/flutter/packages/flutter/lib/src/material/about.dart:140:15: Error: Null safety features are disabled for this library.
Try removing the package language version or setting the language version to 2.10 or higher.
  final Widget? icon;
              ^
../../opt/flutter/packages/flutter/lib/src/material/about.dart:146:15: Error: Null safety features are disabled for this library.
Try removing the package language version or setting the language version to 2.10 or higher.
  final Widget? child;
              ^
../../opt/flutter/packages/flutter/lib/src/material/about.dart:155:15: Error: Null safety features are disabled for this library.
Try removing the package language version or setting the language version to 2.10 or higher.
  final String? applicationName;
              ^
../../opt/flutter/packages/flutter/lib/src/material/about.dart:162:15: Error: Null safety features are disabled for this library.
Try removing the package language version or setting the language version to 2.10 or higher.
  final String? applicationVersion;
              ^
../../opt/flutter/packages/flutter/lib/src/material/about.dart:173:15: Error: Null safety features are disabled for this library.
Try removing the package language version or setting the language version to 2.10 or higher.
  final Widget? applicationIcon;
              ^
../../opt/flutter/packages/flutter/lib/src/material/about.dart:180:15: Error: Null safety features are disabled for this library.
Try removing the package language version or setting the language version to 2.10 or higher.
  final String? applicationLegalese;
              ^
../../opt/flutter/packages/flutter/lib/src/material/about.dart:188:21: Error: Null safety features are disabled for this library.
Try removing the package language version or setting the language version to 2.10 or higher.
  final List<Widget>? aboutBoxChildren;
                    ^
../../opt/flutter/packages/flutter/lib/src/material/about.dart:195:13: Error: Null safety features are disabled for this library.
Try removing the package language version or setting the language version to 2.10 or higher.
  final bool? dense;
            ^
../../opt/flutter/packages/flutter/lib/src/material/about.dart:238:3: Error: Null safety features are disabled for this library.
Try removing the package language version or setting the language version to 2.10 or higher.
  required BuildContext context,
  ^^^^^^^^

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