[Flutter / Error] Locale data has not been initialized, call initializeDateFormatting(<locale>).

• In your pubspec.yaml, add this dependencie package: intl:
• In your highest StatefulWidget (in your dart file), add these imports:

    import 'package:intl/intl.dart';
    import 'package:intl/date_symbol_data_local.dart';

• In its State, override initState add :

      @override
      void initState() {
        super.initState();
        initializeDateFormatting(); //very important
      }

• And the code:

     DateTime now = new DateTime.now();
     var formatter = new DateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");
     String nowFormatted = formatter.format(now);

 

Reference

https://stackoverflow.com/questions/36174033/intl-package-and-date-formatting-strange-behaviour

intl package and date formatting strange behaviour