type 'MaterialPageRoute<dynamic>' is not a subtype of type 'Route<String?>?' of ' in type cast'

Hi, I found an uncertain problem！

Problem description:

I expect to use Navigator.of(context).pop<String> to return a value of a certain type, but the result is always a value of dynamic type.

Code:

// First screen
Navigator.of(context).pushNamed<String>('login').then((String result){
                                  print('login.result runtimeType: ${result.runtimeType}');
                                });

// Second screen
Navigator.of(context).pop<String>('success');

A type error will occur in the above code:

E/flutter (16614): [ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled Exception: type 'MaterialPageRoute<dynamic>' is not a subtype of type 'Route<String>' in type cast
E/flutter (16614): #0      NavigatorState._routeNamed (package:flutter/src/widgets/navigator.dart:3138:55)
E/flutter (16614): #1      NavigatorState.pushNamed (package:flutter/src/widgets/navigator.dart:3190:20)
E/flutter (16614): #2      _Transfer.build.<anonymous closure> (package:example/views/FirstScreen.dart:157:55)
E/flutter (16614): #3      GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:182:24)
E/flutter (16614): #4      TapGestureRecognizer.handleTapUp (package:flutter/src/gestures/tap.dart:504:11)
E/flutter (16614): #5      BaseTapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:282:5)
E/flutter (16614): #6      BaseTapGestureRecognizer.acceptGesture (package:flutter/src/gestures/tap.dart:254:7)
E/flutter (16614): #7      GestureArenaManager.sweep (package:flutter/src/gestures/arena.dart:156:27)
E/flutter (16614): #8      GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:222:20)
E/flutter (16614): #9      GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:198:22)
E/flutter (16614): #10     GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:156:7)
E/flutter (16614): #11     GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:102:7)
E/flutter (16614): #12     GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:86:7)
E/flutter (16614): #13     _rootRunUnary (dart:async/zone.dart:1196:13)
E/flutter (16614): #14     _CustomZone.runUnary (dart:async/zone.dart:1085:19)
E/flutter (16614): #15     _CustomZone.runUnaryGuarded (dart:async/zone.dart:987:7)
E/flutter (16614): #16     _invoke1 (dart:ui/hooks.dart:275:10)
E/flutter (16614): #17     _dispatchPointerDataPacket (dart:ui/hooks.dart:184:5)
E/flutter (16614):

you don't need to make pushNamed() or pop()
just pushNamed("routeName") and pop(value)
you will get right type

@liodali

Thanks @liodali ,
It should be solved by this, closing.
@notescript If you disagree please write in the comments and I will reopen it

https://flutter.dev/docs/cookbook/navigation/returning-data#interactive-example

@VladyslavBondarenko

Hi @VladyslavBondarenko ,
your example used Navigator.push(), return data's type work well.

But, i find if i use Navigator.pushNamed() replace Navigator.push() it throw A type error will occur as same as @notescript showed.

you can check code
here

replace String result by var result,should work for you

@liodali

@liodali use var work for me.

But i think API Navigator.pushNamed() and Navigator.push() should have the same result,even certain a type.

This is a deficiency on flutter's Navigator1/MaterialApp side when routes table is being used. This isn't documented anywhere, but it should've been. The workaround is to stop providing pushNamed any type, but instead typecast to it later:

 final params = (await Navigator.of(context).pushNamed('/xx', arguments: RouteArgs('abc'))) as RouteRetParams;
// params  is now of `RouteRetParams` type

This needs fixing, either on doc or code 's side.

This is also blocking internal migration

This issue is missing a priority label. Please set a priority label when adding the triaged-design label.

I had similar problem, but with auto_route navigation, so I fixed cast issue by adding <type> to CustomRoute declaration:

    CustomRoute<int?>(
      name: RoutesNames.imageSliderFullScreen,
      path: Routes.imageSliderFullScreen,
      page: ImageSliderWithExtendedImageFullScreen,
      customRouteBuilder: dismissablePageRouteBuilder,
    ),

Fix `Navigator.pushNamed<T>()` type checking (flutter#188148)

This thread has been automatically locked since there has not been any recent activity after it was closed. If you are still experiencing a similar issue, please open a new bug, including the output of flutter doctor -v and a minimal reproduction of the issue.

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type 'MaterialPageRoute<dynamic>' is not a subtype of type 'Route<String?>?' of ' in type cast' #57186

Hi, I found an uncertain problem！

Problem description:

Code:

A type error will occur in the above code:

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type 'MaterialPageRoute<dynamic>' is not a subtype of type 'Route<String?>?' of ' in type cast' #57186

Description

Hi, I found an uncertain problem！

Problem description:

Code:

A type error will occur in the above code:

Activity

liodali commented on May 14, 2020

VladyslavBondarenko commented on May 14, 2020

HannibalKcc commented on Jun 15, 2020

liodali commented on Jun 15, 2020

HannibalKcc commented on Jun 16, 2020

celesteking commented on Nov 17, 2020

chunhtai commented on Oct 10, 2022

6 remaining items

flutter-triage-bot commented on Jan 12, 2024

equescodebelike commented on Aug 14, 2025

github-actions commented on Sep 10, 2026

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