Unable to build iOS or Android app after upgrade to Flutter 3.0

Question

After upgrading to Flutter 3.0 I am no longer able to build any of my apps for either iOS or Android and get the same errors in both builds:

: Error: Member not found: 'UnicodeChar'.
  int get UnicodeChar => Char.UnicodeChar;
                              ^^^^^^^^^^^
: Error: Setter not found: 'UnicodeChar'.
  set UnicodeChar(int value) => Char.UnicodeChar = value;

                                     ^^^^^^^^^^^
: Error: Member not found: 'AsciiChar'.
  int get AsciiChar => Char.AsciiChar;
                            ^^^^^^^^^
: Error: Setter not found: 'AsciiChar'.
  set AsciiChar(int value) => Char.AsciiChar = value;

                                   ^^^^^^^^^

and these errors are in the file "src/structs.g.dart" (part of Flutter/Dart as far as I can tell) as follows:

/// {@category Struct}
class _CHAR_INFO__Char_e__Union extends Union {
  @Uint16()
  external int UnicodeChar;
  @Uint8()
  external int AsciiChar;
}

extension CHAR_INFO_Extension on CHAR_INFO {
  int get UnicodeChar => Char.UnicodeChar;
  set UnicodeChar(int value) => Char.UnicodeChar = value;

  int get AsciiChar => Char.AsciiChar;
  set AsciiChar(int value) => Char.AsciiChar = value;
}

I am running VSCode 1.67.1 on macOS Monterey 12.3.1 and flutter doctor -v shows no errors found.

It appears that the file "src/structs.g.dart" seems to be part of the Win32 components in "pub.dartlang.org" but I am not building my apps for Windows (yet).

Any ideas on what I need to do to be able to build for iOS and Android again will be much appreciated.

Thanks

Les

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

Delete the build folder, run flutter clean. I had the same problem with a macOS project and had to delete the macOs folder. Works fine afterwards.

Answer 3

1. Step 1: Delete pod folder in ios.

2. Step 2: uncomment the code at the line # platform :ios, '9.0' in Podfile.

3. Step 3: change line platform :ios, '9.0' to platform :ios, '10.0'

4. Step 4: run : flutter pub upgrade

5. Step 5: cd ios , run pod install

6. Step 6: run pod repo update and sudo gem install cocoapods and run again pod repo update and run pod install

   Step 7: run again project . goodluck

Answer 4

Downgrade flutter to the previous version "flutter downgrade" until an upgrade to flutter 3.0.0 is provided by the owners of all packages you are using in your project.