GlobalKey in CupertinoNavigationBar property triggers "Multiple widgets used the same GlobalKey." when changing route

Steps to Reproduce

Execute flutter run on the code sample
Click the settings icon button in the app bar

Expected results:
No error gets thrown, since doing the same with the equivalent material widgets (Scaffold, AppBar) throws no such error.

Actual results:

══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY
╞═══════════════════════════════════════════════════════════
The following assertion was thrown while finalizing the widget tree:
Multiple widgets used the same GlobalKey.
The key [GlobalKey#cf59a] was used by multiple widgets. The parents of those
widgets were different
widgets that both had the following description:
  IconTheme(color: systemBlue)
A GlobalKey can only be specified on one widget at a time in the widget tree.

When the exception was thrown, this was the stack:
#0      BuildOwner._debugVerifyGlobalKeyReservation.<anonymous
closure>.<anonymous closure>.<anonymous closure>
(package:flutter/src/widgets/framework.dart:2883:13)
#1      _LinkedHashMapMixin.forEach
(dart:collection-patch/compact_hash.dart:617:13)
#2      BuildOwner._debugVerifyGlobalKeyReservation.<anonymous
closure>.<anonymous closure>
(package:flutter/src/widgets/framework.dart:2827:20)
#3      _LinkedHashMapMixin.forEach
(dart:collection-patch/compact_hash.dart:617:13)
#4      BuildOwner._debugVerifyGlobalKeyReservation.<anonymous closure>
(package:flutter/src/widgets/framework.dart:2822:36)
#5      BuildOwner._debugVerifyGlobalKeyReservation
(package:flutter/src/widgets/framework.dart:2891:6)
#6      BuildOwner.finalizeTree.<anonymous closure>
(package:flutter/src/widgets/framework.dart:2950:11)
#7      BuildOwner.finalizeTree
(package:flutter/src/widgets/framework.dart:3032:8)
#8      WidgetsBinding.drawFrame
(package:flutter/src/widgets/binding.dart:885:19)
#9      RendererBinding._handlePersistentFrameCallback
(package:flutter/src/rendering/binding.dart:378:5)
#10     SchedulerBinding._invokeFrameCallback
(package:flutter/src/scheduler/binding.dart:1175:15)
#11     SchedulerBinding.handleDrawFrame
(package:flutter/src/scheduler/binding.dart:1104:9)
#12     SchedulerBinding._handleDrawFrame
(package:flutter/src/scheduler/binding.dart:1015:5)
#13     _invoke (dart:ui/hooks.dart:148:13)
#14     PlatformDispatcher._drawFrame (dart:ui/platform_dispatcher.dart:318:5)
#15     _drawFrame (dart:ui/hooks.dart:115:31)
════════════════════════════════════════════════════════════════════════════════
════════════════════

Another exception was thrown: Multiple widgets used the same GlobalKey.

Another exception was thrown: Multiple widgets used the same GlobalKey.

Another exception was thrown: Duplicate GlobalKey detected in widget tree.

Code sample

import 'package:flutter/cupertino.dart';

void main() => runApp(const CupertinoApp(home: Example()));

class Example extends StatelessWidget {
  const Example({Key? key}) : super(key: key);

  static final GlobalKey settingsButtonKey = GlobalKey();

  @override
  Widget build(BuildContext context) {
    return CupertinoPageScaffold(
      child: Container(),
      navigationBar: CupertinoNavigationBar(
          trailing: CupertinoButton(
            onPressed: () {
              Navigator.push(context, CupertinoPageRoute(builder: (context) => const SettingsPage()));
            },
            child: const Icon(CupertinoIcons.settings),
            key: settingsButtonKey,
          )),
    );
  }
}

class SettingsPage extends StatelessWidget {
  const SettingsPage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return CupertinoPageScaffold(
      child: Container(),
      navigationBar: const CupertinoNavigationBar(middle: Text("Settings")),
    );
  }
}

Logs

[        ] R Hot restart.
[        ] h List all available interactive commands.
[        ] d Detach (terminate "flutter run" but leave application running).
[        ] c Clear the screen
[        ] q Quit (terminate the application on the device).
[        ]  Running with sound null safety 
[        ] An Observatory debugger and profiler on Pixel 3a is available at: http://127.0.0.1:60024/yUcbevZ8ywM=/
[ +557 ms] The Flutter DevTools debugger and profiler on Pixel 3a is available at: http://127.0.0.1:9100?uri=http://127.0.0.1:60024/yUcbevZ8ywM=/
[+6800 ms]
                    ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
                    The following assertion was thrown while finalizing the widget tree:
                    Multiple widgets used the same GlobalKey.
                    The key [GlobalKey#cf82d] was used by multiple widgets. The parents of those widgets were different
                    widgets that both had the following description:
                      IconTheme(color: systemBlue)
                    A GlobalKey can only be specified on one widget at a time in the widget tree.
                    
                    When the exception was thrown, this was the stack:
                    #0      BuildOwner._debugVerifyGlobalKeyReservation.<anonymous closure>.<anonymous closure>.<anonymous closure> (package:flutter/src/widgets/framework.dart:2883:13)
                    #1      _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:617:13)
                    #2      BuildOwner._debugVerifyGlobalKeyReservation.<anonymous closure>.<anonymous closure> (package:flutter/src/widgets/framework.dart:2827:20)
                    #3      _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:617:13)
                    #4      BuildOwner._debugVerifyGlobalKeyReservation.<anonymous closure> (package:flutter/src/widgets/framework.dart:2822:36)
                    #5      BuildOwner._debugVerifyGlobalKeyReservation (package:flutter/src/widgets/framework.dart:2891:6)
                    #6      BuildOwner.finalizeTree.<anonymous closure> (package:flutter/src/widgets/framework.dart:2950:11)
                    #7      BuildOwner.finalizeTree (package:flutter/src/widgets/framework.dart:3032:8)
                    #8      WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:885:19)
                    #9      RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:378:5)
                    #10     SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1175:15)
                    #11     SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1104:9)
                    #12     SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:1015:5)
                    #13     _invoke (dart:ui/hooks.dart:148:13)
                    #14     PlatformDispatcher._drawFrame (dart:ui/platform_dispatcher.dart:318:5)
                    #15     _drawFrame (dart:ui/hooks.dart:115:31)
                    ════════════════════════════════════════════════════════════════════════════════════════════════════

No issues found! (ran in 7.5s)

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The issue is reproducible using the code sample provided above.

Adding the key to the CupertinoNavigationBar itself does not trigger the exception. It seems to be triggered when the key is added to a property of the CupertinoNavigationBar.
I tested with leading, trailing & middle, and the exception was thrown for all 3 properties.

Labeling for further investigation from the team.

logs

flutter: ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
flutter: The following assertion was thrown while finalizing the widget tree:
flutter: Multiple widgets used the same GlobalKey.
flutter: The key [GlobalKey#f6874 Example] was used by multiple widgets. The parents of those widgets were
flutter: different widgets that both had the following description:
flutter:   IconTheme(color: systemBlue)
flutter: A GlobalKey can only be specified on one widget at a time in the widget tree.
flutter:
flutter: When the exception was thrown, this was the stack:
flutter: #0      BuildOwner._debugVerifyGlobalKeyReservation.<anonymous closure>.<anonymous closure>.<anonymous closure> (package:flutter/src/widgets/framework.dart:2950:13)
flutter: #1      _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:620:13)
flutter: #2      BuildOwner._debugVerifyGlobalKeyReservation.<anonymous closure>.<anonymous closure> (package:flutter/src/widgets/framework.dart:2894:20)
flutter: #3      _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:620:13)
flutter: #4      BuildOwner._debugVerifyGlobalKeyReservation.<anonymous closure> (package:flutter/src/widgets/framework.dart:2889:36)
flutter: #5      BuildOwner._debugVerifyGlobalKeyReservation (package:flutter/src/widgets/framework.dart:2958:6)
flutter: #6      BuildOwner.finalizeTree.<anonymous closure> (package:flutter/src/widgets/framework.dart:3017:11)
flutter: #7      BuildOwner.finalizeTree (package:flutter/src/widgets/framework.dart:3099:8)
flutter: #8      WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:870:19)

flutter doctor -v

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! Doctor found issues in 2 categories.

This is a known limitation of CupertinoNavigationBar because on the slide transition, a new nav bar is painted over the existing one, with the child widgets copied over. See the paragraph on transitionBetweenRoutes for more information, and work arounds.

However from this issue, and the duplicate one, it does seem like there's a need to be adjusted, but it will be a fairly sizable rewrite of the transition, so it may not be a quick fix.

This issue is assigned but has had no recent status updates. Please consider unassigning this issue if it is not going to be addressed in the near future. This allows people to have a clearer picture of what work is actually planned. Thanks!

I'm downgrading the priority to p2 as per my last comment. I'm also unassigning this from myself as I'm not actively working on this at the moment. If somebody wants to pick it up before I get to it, please feel free to tag me here or on Discord for help.

As a workaround, set CupertinoNavigationBar.transitionBetweenRoutes or CupertinoSliverNavigationBar.transitionBetweenRoutes to false.

test: canary for a GlobalKey in a Cupertino bar on a push (flutter/fl…

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GlobalKey in CupertinoNavigationBar property triggers "Multiple widgets used the same GlobalKey." when changing route #113409

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GlobalKey in CupertinoNavigationBar property triggers "Multiple widgets used the same GlobalKey." when changing route #113409

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danagbemava-nc commented on Oct 14, 2022

MitchellGoodwin commented on Nov 11, 2022

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flutter-triage-bot commented on Jul 8, 2023

MitchellGoodwin commented on Aug 18, 2023

victorsanni commented on Jun 6, 2025

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