From 5276a8a09c77a40bb44695d08508ae01176c5734 Mon Sep 17 00:00:00 2001
From: iCodePoet <dev.code.poet@gmail.com>
Date: Wed, 19 Aug 2026 02:41:43 +0900
Subject: [PATCH] [go_router] Fix "Bad state: Future already completed" when a
 route with onExit is popped twice

---
 packages/go_router/CHANGELOG.md           |  4 +++
 packages/go_router/lib/src/match.dart     |  8 +++++
 packages/go_router/pubspec.yaml           |  2 +-
 packages/go_router/test/on_exit_test.dart | 39 +++++++++++++++++++++++
 4 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/packages/go_router/CHANGELOG.md b/packages/go_router/CHANGELOG.md
index ef05a190eb98..a05a51aaa089 100644
--- a/packages/go_router/CHANGELOG.md
+++ b/packages/go_router/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 17.5.1
+
+- Fixes a `StateError` ("Bad state: Future already completed") when a route with an `onExit` callback is popped twice before the navigator rebuilds.
+
 ## 17.5.0
 
 - Adds route `metadata` support, including inheritance and override behavior with exposure on `GoRouterState`.
diff --git a/packages/go_router/lib/src/match.dart b/packages/go_router/lib/src/match.dart
index bc7de56d39fa..8d0b27336ebd 100644
--- a/packages/go_router/lib/src/match.dart
+++ b/packages/go_router/lib/src/match.dart
@@ -458,7 +458,15 @@ class ImperativeRouteMatch extends RouteMatch {
 
   /// Called when the corresponding [Route] associated with this route match is
   /// completed.
+  ///
+  /// A route match can be completed more than once when the same route is
+  /// popped again before the navigator has rebuilt; for example, two back
+  /// events in quick succession while an `onExit` callback defers the pop to a
+  /// microtask. Only the first completion is reported; later ones are ignored.
   void complete([dynamic value]) {
+    if (completer.isCompleted) {
+      return;
+    }
     completer.complete(value);
   }
 
diff --git a/packages/go_router/pubspec.yaml b/packages/go_router/pubspec.yaml
index d8641367c8d9..fc2eac3ae1e2 100644
--- a/packages/go_router/pubspec.yaml
+++ b/packages/go_router/pubspec.yaml
@@ -1,7 +1,7 @@
 name: go_router
 description: A declarative router for Flutter based on Navigation 2 supporting
   deep linking, data-driven routes and more
-version: 17.5.0
+version: 17.5.1
 repository: https://github.com/flutter/packages/tree/main/packages/go_router
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+go_router%22
 
diff --git a/packages/go_router/test/on_exit_test.dart b/packages/go_router/test/on_exit_test.dart
index 990ee9a9a6a3..b068adaac2e3 100644
--- a/packages/go_router/test/on_exit_test.dart
+++ b/packages/go_router/test/on_exit_test.dart
@@ -529,6 +529,45 @@ void main() {
     expect(find.byKey(homeKey), findsNothing);
   });
 
+  // Regression test for https://github.com/flutter/flutter/issues/191280
+  testWidgets('popping a route with onExit twice before the navigator rebuilds does not throw', (
+    WidgetTester tester,
+  ) async {
+    final homeKey = UniqueKey();
+    final detailKey = UniqueKey();
+
+    final GoRouter router = await createRouter(
+      <RouteBase>[
+        GoRoute(
+          path: '/',
+          builder: (_, _) => DummyScreen(key: homeKey),
+          routes: <RouteBase>[
+            GoRoute(
+              path: 'detail',
+              onExit: (_, _) => true,
+              builder: (_, _) => DummyScreen(key: detailKey),
+            ),
+          ],
+        ),
+      ],
+      tester,
+    );
+
+    final Future<Object?> pushFuture = router.push('/detail');
+    await tester.pumpAndSettle();
+    expect(find.byKey(detailKey), findsOneWidget);
+
+    // Two back events arrive before the deferred pop is applied — e.g. a user
+    // tapping the back button twice in quick succession.
+    router.pop('first');
+    router.pop('second');
+    await tester.pumpAndSettle();
+
+    expect(tester.takeException(), isNull);
+    expect(find.byKey(homeKey), findsOneWidget);
+    expect(await pushFuture, 'first');
+  });
+
   // Regression test for https://github.com/flutter/flutter/issues/137829
   testWidgets('back button works synchronously with ShellRoute', (WidgetTester tester) async {
     var allow = false;