This error is produced when I upgrade flutter and switch to the master channel

'SchedulerBinding' is from 'package:flutter/src/scheduler/binding.dart' ('../../../dev/flutter_linux_2.8.1-stable/flutter/packages/flutter/lib/src/scheduler/binding.dart').
ERROR:     SchedulerBinding.instance?.addPostFrameCallback((_) => onReady());

I was forced to upgrade. What should I do?