From 98991576917a4d1c9cdf617e95952d134379d941 Mon Sep 17 00:00:00 2001
From: Broto <brotoo25@gmail.com>
Date: Mon, 6 Jul 2026 16:54:29 +1200
Subject: [PATCH] [go_router] Fix popRoute crash when a shell route's navigator
 is not mounted

GoRouterDelegate._findCurrentNavigators force-unwraps each shell
navigator's state while walking the current configuration. When the
system back button is pressed while the configuration references a
shell route whose navigator is not mounted (e.g. mid-redirect away
from the shell, or while resuming from background), popRoute throws
'Null check operator used on a null value'.

Stop walking when a shell navigator is not mounted, matching the
null-tolerant handling canPop already uses for the same state.

Fixes flutter/flutter#188993
---
 packages/go_router/lib/src/delegate.dart      |  8 ++++++-
 ...ix_poproute_unmounted_shell_navigator.yaml |  5 ++++
 packages/go_router/test/delegate_test.dart    | 24 +++++++++++++++++++
 3 files changed, 36 insertions(+), 1 deletion(-)
 create mode 100644 packages/go_router/pending_changelogs/fix_poproute_unmounted_shell_navigator.yaml

diff --git a/packages/go_router/lib/src/delegate.dart b/packages/go_router/lib/src/delegate.dart
index 8b43fa716530..858c8c231412 100644
--- a/packages/go_router/lib/src/delegate.dart
+++ b/packages/go_router/lib/src/delegate.dart
@@ -118,7 +118,13 @@ class GoRouterDelegate extends RouterDelegate<RouteMatchList> with ChangeNotifie
 
     RouteMatchBase walker = currentConfiguration.matches.last;
     while (walker is ShellRouteMatch) {
-      final NavigatorState potentialCandidate = walker.navigatorKey.currentState!;
+      final NavigatorState? potentialCandidate = walker.navigatorKey.currentState;
+      if (potentialCandidate == null) {
+        // Stop if the shell route's navigator is not mounted, e.g. when the
+        // configuration references a shell route whose widget tree has not
+        // been built yet or has already been removed.
+        break;
+      }
 
       final ModalRoute<dynamic>? modalRoute = ModalRoute.of(potentialCandidate.context);
       if (modalRoute == null || !modalRoute.isCurrent) {
diff --git a/packages/go_router/pending_changelogs/fix_poproute_unmounted_shell_navigator.yaml b/packages/go_router/pending_changelogs/fix_poproute_unmounted_shell_navigator.yaml
new file mode 100644
index 000000000000..b5f5156a57be
--- /dev/null
+++ b/packages/go_router/pending_changelogs/fix_poproute_unmounted_shell_navigator.yaml
@@ -0,0 +1,5 @@
+changelog: |
+  - Fixes `popRoute()` crashing with "Null check operator used on a null value"
+    when the current configuration references a shell route whose navigator is
+    not mounted.
+version: patch
diff --git a/packages/go_router/test/delegate_test.dart b/packages/go_router/test/delegate_test.dart
index 12d2d914ad6a..b543c1ca7fa2 100644
--- a/packages/go_router/test/delegate_test.dart
+++ b/packages/go_router/test/delegate_test.dart
@@ -343,6 +343,30 @@ void main() {
       ], tester);
       expect(await goRouter.routerDelegate.popRoute(), isFalse);
     });
+
+    testWidgets('popRoute does not throw when a shell navigator in the configuration '
+        'is not mounted', (WidgetTester tester) async {
+      final GoRouter goRouter = await createRouter(<RouteBase>[
+        GoRoute(path: '/', builder: (_, _) => const Text('Home')),
+        ShellRoute(
+          builder: (_, _, Widget child) => child,
+          routes: <RouteBase>[
+            GoRoute(path: '/dashboard', builder: (_, _) => const Text('Dashboard')),
+          ],
+        ),
+      ], tester);
+
+      // Simulate the transient state where the configuration references a
+      // shell route whose navigator is not (or no longer) mounted, e.g. while
+      // the widget tree rebuilds during a redirect or after resuming from
+      // background.
+      goRouter.routerDelegate.currentConfiguration = goRouter.configuration.findMatch(
+        Uri.parse('/dashboard'),
+      );
+
+      // Should not throw "Null check operator used on a null value".
+      expect(await goRouter.routerDelegate.popRoute(), isFalse);
+    });
   });
 
   group('push', () {