diff --git a/assets/l10n/app_en.arb b/assets/l10n/app_en.arb
index ba02a819b1..0764d87955 100644
--- a/assets/l10n/app_en.arb
+++ b/assets/l10n/app_en.arb
@@ -206,8 +206,8 @@
       "url": {"type": "String", "example": "http://example.com/"}
     }
   },
-  "errorLoginCouldNotConnectTitle": "Could not connect",
-  "@errorLoginCouldNotConnectTitle": {
+  "errorCouldNotConnectTitle": "Could not connect",
+  "@errorCouldNotConnectTitle": {
     "description": "Error title when the app could not connect to the server."
   },
   "errorMessageDoesNotSeemToExist": "That message does not seem to exist.",
@@ -515,6 +515,13 @@
   "@topicValidationErrorMandatoryButEmpty": {
     "description": "Topic validation error when topic is required but was empty."
   },
+  "errorInvalidApiKeyMessage": "Your account at {url} could not be authenticated. Please try logging in again or use another account.",
+  "@errorInvalidApiKeyMessage": {
+    "description": "Error message in the dialog for invalid API key.",
+    "placeholders": {
+      "url": {"type": "String", "example": "http://chat.example.com/"}
+    }
+  },
   "errorInvalidResponse": "The server sent an invalid response",
   "@errorInvalidResponse": {
     "description": "Error message when an API call returned an invalid response."
diff --git a/lib/generated/l10n/zulip_localizations.dart b/lib/generated/l10n/zulip_localizations.dart
index 9be039ef72..453ae35357 100644
--- a/lib/generated/l10n/zulip_localizations.dart
+++ b/lib/generated/l10n/zulip_localizations.dart
@@ -391,7 +391,7 @@ abstract class ZulipLocalizations {
   ///
   /// In en, this message translates to:
   /// **'Could not connect'**
-  String get errorLoginCouldNotConnectTitle;
+  String get errorCouldNotConnectTitle;
 
   /// Error message when loading a message that does not exist.
   ///
@@ -795,6 +795,12 @@ abstract class ZulipLocalizations {
   /// **'Topics are required in this organization.'**
   String get topicValidationErrorMandatoryButEmpty;
 
+  /// Error message in the dialog for invalid API key.
+  ///
+  /// In en, this message translates to:
+  /// **'Your account at {url} could not be authenticated. Please try logging in again or use another account.'**
+  String errorInvalidApiKeyMessage(String url);
+
   /// Error message when an API call returned an invalid response.
   ///
   /// In en, this message translates to:
diff --git a/lib/generated/l10n/zulip_localizations_ar.dart b/lib/generated/l10n/zulip_localizations_ar.dart
index 2e59dae8af..28e5d4c973 100644
--- a/lib/generated/l10n/zulip_localizations_ar.dart
+++ b/lib/generated/l10n/zulip_localizations_ar.dart
@@ -174,7 +174,7 @@ class ZulipLocalizationsAr extends ZulipLocalizations {
   }
 
   @override
-  String get errorLoginCouldNotConnectTitle => 'Could not connect';
+  String get errorCouldNotConnectTitle => 'Could not connect';
 
   @override
   String get errorMessageDoesNotSeemToExist => 'That message does not seem to exist.';
@@ -399,6 +399,11 @@ class ZulipLocalizationsAr extends ZulipLocalizations {
   @override
   String get topicValidationErrorMandatoryButEmpty => 'Topics are required in this organization.';
 
+  @override
+  String errorInvalidApiKeyMessage(String url) {
+    return 'Your account at $url could not be authenticated. Please try logging in again or use another account.';
+  }
+
   @override
   String get errorInvalidResponse => 'The server sent an invalid response';
 
diff --git a/lib/generated/l10n/zulip_localizations_en.dart b/lib/generated/l10n/zulip_localizations_en.dart
index a0e86b7d35..2987799e77 100644
--- a/lib/generated/l10n/zulip_localizations_en.dart
+++ b/lib/generated/l10n/zulip_localizations_en.dart
@@ -174,7 +174,7 @@ class ZulipLocalizationsEn extends ZulipLocalizations {
   }
 
   @override
-  String get errorLoginCouldNotConnectTitle => 'Could not connect';
+  String get errorCouldNotConnectTitle => 'Could not connect';
 
   @override
   String get errorMessageDoesNotSeemToExist => 'That message does not seem to exist.';
@@ -399,6 +399,11 @@ class ZulipLocalizationsEn extends ZulipLocalizations {
   @override
   String get topicValidationErrorMandatoryButEmpty => 'Topics are required in this organization.';
 
+  @override
+  String errorInvalidApiKeyMessage(String url) {
+    return 'Your account at $url could not be authenticated. Please try logging in again or use another account.';
+  }
+
   @override
   String get errorInvalidResponse => 'The server sent an invalid response';
 
diff --git a/lib/generated/l10n/zulip_localizations_ja.dart b/lib/generated/l10n/zulip_localizations_ja.dart
index 6e7f1559ac..93c49994fd 100644
--- a/lib/generated/l10n/zulip_localizations_ja.dart
+++ b/lib/generated/l10n/zulip_localizations_ja.dart
@@ -174,7 +174,7 @@ class ZulipLocalizationsJa extends ZulipLocalizations {
   }
 
   @override
-  String get errorLoginCouldNotConnectTitle => 'Could not connect';
+  String get errorCouldNotConnectTitle => 'Could not connect';
 
   @override
   String get errorMessageDoesNotSeemToExist => 'That message does not seem to exist.';
@@ -399,6 +399,11 @@ class ZulipLocalizationsJa extends ZulipLocalizations {
   @override
   String get topicValidationErrorMandatoryButEmpty => 'Topics are required in this organization.';
 
+  @override
+  String errorInvalidApiKeyMessage(String url) {
+    return 'Your account at $url could not be authenticated. Please try logging in again or use another account.';
+  }
+
   @override
   String get errorInvalidResponse => 'The server sent an invalid response';
 
diff --git a/lib/generated/l10n/zulip_localizations_nb.dart b/lib/generated/l10n/zulip_localizations_nb.dart
index cabd4897e9..a04de46a73 100644
--- a/lib/generated/l10n/zulip_localizations_nb.dart
+++ b/lib/generated/l10n/zulip_localizations_nb.dart
@@ -174,7 +174,7 @@ class ZulipLocalizationsNb extends ZulipLocalizations {
   }
 
   @override
-  String get errorLoginCouldNotConnectTitle => 'Could not connect';
+  String get errorCouldNotConnectTitle => 'Could not connect';
 
   @override
   String get errorMessageDoesNotSeemToExist => 'That message does not seem to exist.';
@@ -399,6 +399,11 @@ class ZulipLocalizationsNb extends ZulipLocalizations {
   @override
   String get topicValidationErrorMandatoryButEmpty => 'Topics are required in this organization.';
 
+  @override
+  String errorInvalidApiKeyMessage(String url) {
+    return 'Your account at $url could not be authenticated. Please try logging in again or use another account.';
+  }
+
   @override
   String get errorInvalidResponse => 'The server sent an invalid response';
 
diff --git a/lib/generated/l10n/zulip_localizations_pl.dart b/lib/generated/l10n/zulip_localizations_pl.dart
index 0a2a2bf1d7..1c30ed0291 100644
--- a/lib/generated/l10n/zulip_localizations_pl.dart
+++ b/lib/generated/l10n/zulip_localizations_pl.dart
@@ -174,7 +174,7 @@ class ZulipLocalizationsPl extends ZulipLocalizations {
   }
 
   @override
-  String get errorLoginCouldNotConnectTitle => 'Nie można połączyć';
+  String get errorCouldNotConnectTitle => 'Could not connect';
 
   @override
   String get errorMessageDoesNotSeemToExist => 'Taka wiadomość raczej nie istnieje.';
@@ -399,6 +399,11 @@ class ZulipLocalizationsPl extends ZulipLocalizations {
   @override
   String get topicValidationErrorMandatoryButEmpty => 'Wątki są wymagane przez tę organizację.';
 
+  @override
+  String errorInvalidApiKeyMessage(String url) {
+    return 'Your account at $url could not be authenticated. Please try logging in again or use another account.';
+  }
+
   @override
   String get errorInvalidResponse => 'Nieprawidłowa odpowiedź serwera';
 
diff --git a/lib/generated/l10n/zulip_localizations_ru.dart b/lib/generated/l10n/zulip_localizations_ru.dart
index 99bd72c62f..3d5e7fa6fb 100644
--- a/lib/generated/l10n/zulip_localizations_ru.dart
+++ b/lib/generated/l10n/zulip_localizations_ru.dart
@@ -174,7 +174,7 @@ class ZulipLocalizationsRu extends ZulipLocalizations {
   }
 
   @override
-  String get errorLoginCouldNotConnectTitle => 'Не удалось подключиться';
+  String get errorCouldNotConnectTitle => 'Could not connect';
 
   @override
   String get errorMessageDoesNotSeemToExist => 'Это сообщение, похоже, отсутствует.';
@@ -399,6 +399,11 @@ class ZulipLocalizationsRu extends ZulipLocalizations {
   @override
   String get topicValidationErrorMandatoryButEmpty => 'Темы обязательны в этой организации.';
 
+  @override
+  String errorInvalidApiKeyMessage(String url) {
+    return 'Your account at $url could not be authenticated. Please try logging in again or use another account.';
+  }
+
   @override
   String get errorInvalidResponse => 'Получен недопустимый ответ сервера';
 
diff --git a/lib/generated/l10n/zulip_localizations_sk.dart b/lib/generated/l10n/zulip_localizations_sk.dart
index 13646eafd5..ea1929139b 100644
--- a/lib/generated/l10n/zulip_localizations_sk.dart
+++ b/lib/generated/l10n/zulip_localizations_sk.dart
@@ -174,7 +174,7 @@ class ZulipLocalizationsSk extends ZulipLocalizations {
   }
 
   @override
-  String get errorLoginCouldNotConnectTitle => 'Nepodarilo sa pripojiť';
+  String get errorCouldNotConnectTitle => 'Could not connect';
 
   @override
   String get errorMessageDoesNotSeemToExist => 'Správa zrejme neexistuje.';
@@ -399,6 +399,11 @@ class ZulipLocalizationsSk extends ZulipLocalizations {
   @override
   String get topicValidationErrorMandatoryButEmpty => 'Topics are required in this organization.';
 
+  @override
+  String errorInvalidApiKeyMessage(String url) {
+    return 'Your account at $url could not be authenticated. Please try logging in again or use another account.';
+  }
+
   @override
   String get errorInvalidResponse => 'Server poslal nesprávnu odpoveď';
 
diff --git a/lib/log.dart b/lib/log.dart
index e3261f8cba..31b9469e8f 100644
--- a/lib/log.dart
+++ b/lib/log.dart
@@ -31,7 +31,8 @@ bool debugLog(String message) {
   return true;
 }
 
-typedef ReportErrorCallback = void Function(String? message, {String? details});
+typedef ReportErrorCancellablyCallback = void Function(String? message, {String? details});
+typedef ReportErrorCallback = void Function(String message, {String? details});
 
 /// Show the user an error message, without requiring them to interact with it.
 ///
@@ -48,9 +49,20 @@ typedef ReportErrorCallback = void Function(String? message, {String? details});
 // This gets set in [ZulipApp].  We need this indirection to keep `lib/log.dart`
 // from importing widget code, because the file is a dependency for the rest of
 // the app.
-ReportErrorCallback reportErrorToUserBriefly = defaultReportErrorToUserBriefly;
+ReportErrorCancellablyCallback reportErrorToUserBriefly = reportErrorToConsole;
 
-void defaultReportErrorToUserBriefly(String? message, {String? details}) {
+/// Show the user a dismissable error message in a modal popup.
+///
+/// Typically this shows an [AlertDialog] containing the message.
+/// If called before the app's widget tree is ready (see [ZulipApp.ready]),
+/// then we give up on showing the message to the user,
+/// and just log the message to the console.
+// This gets set in [ZulipApp].  We need this indirection to keep `lib/log.dart`
+// from importing widget code, because the file is a dependency for the rest of
+// the app.
+ReportErrorCallback reportErrorToUserModally = reportErrorToConsole;
+
+void reportErrorToConsole(String? message, {String? details}) {
   // Error dismissing is a no-op to the default handler.
   if (message == null) return;
   // If this callback is still in place, then the app's widget tree
diff --git a/lib/model/actions.dart b/lib/model/actions.dart
new file mode 100644
index 0000000000..76d88d250b
--- /dev/null
+++ b/lib/model/actions.dart
@@ -0,0 +1,36 @@
+import 'dart:async';
+
+import '../notifications/receive.dart';
+import 'store.dart';
+
+// TODO: Make this a part of GlobalStore
+Future<void> logOutAccount(GlobalStore globalStore, int accountId) async {
+  final account = globalStore.getAccount(accountId);
+  if (account == null) return; // TODO(log)
+
+  // Unawaited, to not block removing the account on this request.
+  unawaited(unregisterToken(globalStore, accountId));
+
+  await globalStore.removeAccount(accountId);
+}
+
+Future<void> unregisterToken(GlobalStore globalStore, int accountId) async {
+  final account = globalStore.getAccount(accountId);
+  if (account == null) return; // TODO(log)
+
+  // TODO(#322) use actual acked push token; until #322, this is just null.
+  final token = account.ackedPushToken
+      // Try the current token as a fallback; maybe the server has registered
+      // it and we just haven't recorded that fact in the client.
+      ?? NotificationService.instance.token.value;
+  if (token == null) return;
+
+  final connection = globalStore.apiConnectionFromAccount(account);
+  try {
+    await NotificationService.unregisterToken(connection, token: token);
+  } catch (e) {
+    // TODO retry? handle failures?
+  } finally {
+    connection.close();
+  }
+}
diff --git a/lib/model/store.dart b/lib/model/store.dart
index 7603c7f452..6838028933 100644
--- a/lib/model/store.dart
+++ b/lib/model/store.dart
@@ -19,6 +19,7 @@ import '../api/backoff.dart';
 import '../api/route/realm.dart';
 import '../log.dart';
 import '../notifications/receive.dart';
+import 'actions.dart';
 import 'autocomplete.dart';
 import 'database.dart';
 import 'emoji.dart';
@@ -149,7 +150,29 @@ abstract class GlobalStore extends ChangeNotifier {
   /// and/or [perAccountSync].
   Future<PerAccountStore> loadPerAccount(int accountId) async {
     assert(_accounts.containsKey(accountId));
-    final store = await doLoadPerAccount(accountId);
+    final realmUrl = getAccount(accountId)!.realmUrl;
+    final PerAccountStore store;
+    try {
+      store = await doLoadPerAccount(accountId);
+    } catch (e) {
+      switch (e) {
+        case HttpException(httpStatus: 401):
+          // The API key is invalid and the store can never be loaded
+          // unless the user retries manually.
+          final zulipLocalizations = GlobalLocalizations.zulipLocalizations;
+          reportErrorToUserModally(
+            zulipLocalizations.errorCouldNotConnectTitle,
+            details: zulipLocalizations.errorInvalidApiKeyMessage(
+              realmUrl.toString()));
+          // The account could be logged out from the choose-account page.
+          if (_accounts.containsKey(accountId)) {
+            await logOutAccount(this, accountId);
+          }
+          throw AccountNotFoundException();
+        default:
+          rethrow;
+      }
+    }
     if (!_accounts.containsKey(accountId)) {
       // [removeAccount] was called during [doLoadPerAccount].
       store.dispose();
@@ -913,12 +936,19 @@ class UpdateMachine {
       try {
         return await registerQueue(connection);
       } catch (e, s) {
-        assert(debugLog('Error fetching initial snapshot: $e'));
-        // Print stack trace in its own log entry; log entries are truncated
-        // at 1 kiB (at least on Android), and stack can be longer than that.
-        assert(debugLog('Stack:\n$s'));
+        // TODO(#890): tell user if initial-fetch errors persist, or look non-transient
+        switch (e) {
+          case HttpException(httpStatus: 401):
+            // We cannot recover from this error through retrying.
+            // Leave it to [GlobalStore.loadPerAccount].
+            rethrow;
+          default:
+            assert(debugLog('Error fetching initial snapshot: $e'));
+            // Print stack trace in its own log entry; log entries are truncated
+            // at 1 kiB (at least on Android), and stack can be longer than that.
+            assert(debugLog('Stack:\n$s'));
+        }
         assert(debugLog('Backing off, then will retry…'));
-        // TODO tell user if initial-fetch errors persist, or look non-transient
         await (backoffMachine ??= BackoffMachine()).wait();
         assert(debugLog('… Backoff wait complete, retrying initial fetch.'));
       }
@@ -1177,6 +1207,7 @@ class UpdateMachine {
     store.isLoading = true;
 
     bool isUnexpected;
+    // TODO(#1054): handle auth failure
     switch (error) {
       case ZulipApiException(code: 'BAD_EVENT_QUEUE_ID'):
         assert(debugLog('Lost event queue for $store.  Replacing…'));
@@ -1218,8 +1249,17 @@ class UpdateMachine {
       if (_disposed) return;
     }
 
-    await store._globalStore._reloadPerAccount(store.accountId);
-    assert(_disposed);
+    try {
+      await store._globalStore._reloadPerAccount(store.accountId);
+    } on AccountNotFoundException {
+      // The account was logged out while we retry to replace the store,
+      // but that's OK as long as other code will be removing it from the UI
+      // (usually by using [routeToRemoveOnLogout]).
+      assert(debugLog('… Event queue not replaced; account logged out.'));
+      return;
+    } finally {
+      assert(_disposed);
+    }
     assert(debugLog('… Event queue replaced.'));
   }
 
diff --git a/lib/widgets/actions.dart b/lib/widgets/actions.dart
index 86c6e44875..2df502ec6c 100644
--- a/lib/widgets/actions.dart
+++ b/lib/widgets/actions.dart
@@ -15,44 +15,9 @@ import '../api/model/narrow.dart';
 import '../api/route/messages.dart';
 import '../generated/l10n/zulip_localizations.dart';
 import '../model/narrow.dart';
-import '../model/store.dart';
-import '../notifications/receive.dart';
 import 'dialog.dart';
 import 'store.dart';
 
-Future<void> logOutAccount(BuildContext context, int accountId) async {
-  final globalStore = GlobalStoreWidget.of(context);
-
-  final account = globalStore.getAccount(accountId);
-  if (account == null) return; // TODO(log)
-
-  // Unawaited, to not block removing the account on this request.
-  unawaited(unregisterToken(globalStore, accountId));
-
-  await globalStore.removeAccount(accountId);
-}
-
-Future<void> unregisterToken(GlobalStore globalStore, int accountId) async {
-  final account = globalStore.getAccount(accountId);
-  if (account == null) return; // TODO(log)
-
-  // TODO(#322) use actual acked push token; until #322, this is just null.
-  final token = account.ackedPushToken
-    // Try the current token as a fallback; maybe the server has registered
-    // it and we just haven't recorded that fact in the client.
-    ?? NotificationService.instance.token.value;
-  if (token == null) return;
-
-  final connection = globalStore.apiConnectionFromAccount(account);
-  try {
-    await NotificationService.unregisterToken(connection, token: token);
-  } catch (e) {
-    // TODO retry? handle failures?
-  } finally {
-    connection.close();
-  }
-}
-
 Future<void> markNarrowAsRead(BuildContext context, Narrow narrow) async {
   final store = PerAccountStoreWidget.of(context);
   final connection = store.connection;
diff --git a/lib/widgets/app.dart b/lib/widgets/app.dart
index 9525dffdfe..0608866972 100644
--- a/lib/widgets/app.dart
+++ b/lib/widgets/app.dart
@@ -6,11 +6,11 @@ import 'package:flutter/scheduler.dart';
 
 import '../generated/l10n/zulip_localizations.dart';
 import '../log.dart';
+import '../model/actions.dart';
 import '../model/localizations.dart';
 import '../model/store.dart';
 import '../notifications/display.dart';
 import 'about_zulip.dart';
-import 'actions.dart';
 import 'dialog.dart';
 import 'home.dart';
 import 'login.dart';
@@ -84,7 +84,8 @@ class ZulipApp extends StatefulWidget {
   @visibleForTesting
   static void debugReset() {
     _snackBarCount = 0;
-    reportErrorToUserBriefly = defaultReportErrorToUserBriefly;
+    reportErrorToUserBriefly = reportErrorToConsole;
+    reportErrorToUserModally = reportErrorToConsole;
     _ready.dispose();
     _ready = ValueNotifier(false);
   }
@@ -128,10 +129,21 @@ class ZulipApp extends StatefulWidget {
     newSnackBar.closed.whenComplete(() => _snackBarCount--);
   }
 
+  /// The callback we normally use as [reportErrorToUserModally].
+  static void _reportErrorToUserModally(String message, {String? details}) {
+    assert(_ready.value);
+
+    showErrorDialog(
+      context: navigatorKey.currentContext!,
+      title: message,
+      message: details);
+  }
+
   void _declareReady() {
     assert(navigatorKey.currentContext != null);
     _ready.value = true;
     reportErrorToUserBriefly = _reportErrorToUserBriefly;
+    reportErrorToUserModally = _reportErrorToUserModally;
   }
 
   @override
@@ -187,7 +199,13 @@ class _ZulipAppState extends State<ZulipApp> with WidgetsBindingObserver {
           theme: themeData,
 
           navigatorKey: ZulipApp.navigatorKey,
-          navigatorObservers: widget.navigatorObservers ?? const [],
+          navigatorObservers: [
+            if (widget.navigatorObservers != null)
+              ...widget.navigatorObservers!,
+            // This must be the last item to maintain the invariant
+            // that the navigator stack is always non-empty.
+            _EmptyStackNavigatorObserver(),
+          ],
           builder: (BuildContext context, Widget? child) {
             if (!ZulipApp.ready.value) {
               SchedulerBinding.instance.addPostFrameCallback(
@@ -218,6 +236,39 @@ class _ZulipAppState extends State<ZulipApp> with WidgetsBindingObserver {
   }
 }
 
+/// Pushes a route whenever the observed navigator stack becomes empty.
+class _EmptyStackNavigatorObserver extends NavigatorObserver {
+  void _pushRouteIfEmptyStack() async {
+    final navigator = await ZulipApp.navigator;
+    bool isEmptyStack = true;
+    // TODO: find a better way to inspect the navigator stack
+    navigator.popUntil((route) {
+      isEmptyStack = false;
+      return true; // never actually pops
+    });
+    if (isEmptyStack) {
+      unawaited(navigator.push(
+        MaterialWidgetRoute(page: const ChooseAccountPage())));
+    }
+  }
+
+  @override
+  void didRemove(Route<void> route, Route<void>? previousRoute) async {
+    if (previousRoute == null) {
+      // The route removed is the bottom-most one.
+      _pushRouteIfEmptyStack();
+    }
+  }
+
+  @override
+  void didPop(Route<void> route, Route<void>? previousRoute) async {
+    if (previousRoute == null) {
+      // The route popped is the bottom-most one.
+      _pushRouteIfEmptyStack();
+    }
+  }
+}
+
 class ChooseAccountPage extends StatelessWidget {
   const ChooseAccountPage({super.key});
 
@@ -249,7 +300,7 @@ class ChooseAccountPage extends StatelessWidget {
                   actionButtonText: zulipLocalizations.logOutConfirmationDialogConfirmButton,
                   onActionButtonPress: () {
                     // TODO error handling if db write fails?
-                    logOutAccount(context, accountId);
+                    logOutAccount(GlobalStoreWidget.of(context), accountId);
                   });
               },
               child: Text(zulipLocalizations.chooseAccountPageLogOutButton)),
diff --git a/lib/widgets/login.dart b/lib/widgets/login.dart
index ce1cf09438..64a0210525 100644
--- a/lib/widgets/login.dart
+++ b/lib/widgets/login.dart
@@ -176,7 +176,7 @@ class _AddAccountPageState extends State<AddAccountPage> {
         // TODO(#105) give more helpful feedback; see `fetchServerSettings`
         //   in zulip-mobile's src/message/fetchActions.js.
         showErrorDialog(context: context,
-          title: zulipLocalizations.errorLoginCouldNotConnectTitle,
+          title: zulipLocalizations.errorCouldNotConnectTitle,
           message: zulipLocalizations.errorLoginCouldNotConnect(url.toString()));
         return;
       }
diff --git a/test/model/message_test.dart b/test/model/message_test.dart
index 43f17be61a..9c9a940d42 100644
--- a/test/model/message_test.dart
+++ b/test/model/message_test.dart
@@ -77,18 +77,6 @@ void main() {
     checkNotified(count: messageList.fetched ? messages.length : 0);
   }
 
-  test('disposing multiple registered MessageListView instances', () async {
-    // Regression test for: https://github.com/zulip/zulip-flutter/issues/810
-    await prepare(narrow: const MentionsNarrow());
-    MessageListView.init(store: store, narrow: const StarredMessagesNarrow());
-    check(store.debugMessageListViews).length.equals(2);
-
-    // When disposing, the [MessageListView]s are expected to unregister
-    // themselves from the message store.
-    store.dispose();
-    check(store.debugMessageListViews).isEmpty();
-  });
-
   group('reconcileMessages', () {
     test('from empty', () async {
       await prepare();
diff --git a/test/model/store_test.dart b/test/model/store_test.dart
index c8c6b4c266..5b192a7c55 100644
--- a/test/model/store_test.dart
+++ b/test/model/store_test.dart
@@ -7,13 +7,13 @@ import 'package:flutter/foundation.dart';
 import 'package:http/http.dart' as http;
 import 'package:test/scaffolding.dart';
 import 'package:zulip/api/core.dart';
+import 'package:zulip/api/exception.dart';
 import 'package:zulip/api/model/events.dart';
 import 'package:zulip/api/model/model.dart';
 import 'package:zulip/api/route/events.dart';
 import 'package:zulip/api/route/messages.dart';
 import 'package:zulip/api/route/realm.dart';
-import 'package:zulip/model/message_list.dart';
-import 'package:zulip/model/narrow.dart';
+import 'package:zulip/model/actions.dart';
 import 'package:zulip/log.dart';
 import 'package:zulip/model/store.dart';
 import 'package:zulip/notifications/receive.dart';
@@ -122,6 +122,39 @@ void main() {
     check(completers(1)).length.equals(1);
   });
 
+  test('GlobalStore.perAccount loading fails with HTTP status code 401', () => awaitFakeAsync((async) async {
+    addTearDown(testBinding.reset);
+
+    await testBinding.globalStore.insertAccount(eg.selfAccount.toCompanion(false));
+    testBinding.globalStore.loadPerAccountException = ZulipApiException(
+      routeName: '/register', code: 'UNAUTHORIZED', httpStatus: 401,
+      data: {}, message: '');
+    await check(testBinding.globalStore.perAccount(eg.selfAccount.id))
+      .throws<AccountNotFoundException>();
+
+    check(testBinding.globalStore.takeDoRemoveAccountCalls())
+      .single.equals(eg.selfAccount.id);
+  }));
+
+  test('GlobalStore.perAccount account is logged out while loading; then fails with HTTP status code 401', () => awaitFakeAsync((async) async {
+    addTearDown(testBinding.reset);
+
+    await testBinding.globalStore.insertAccount(eg.selfAccount.toCompanion(false));
+
+    testBinding.globalStore.loadPerAccountDuration = Duration(seconds: 2);
+    testBinding.globalStore.loadPerAccountException = ZulipApiException(
+      routeName: '/register', code: 'UNAUTHORIZED', httpStatus: 401,
+      data: {}, message: '');
+    final future = testBinding.globalStore.perAccount(eg.selfAccount.id);
+    check(testBinding.globalStore.takeDoRemoveAccountCalls()).isEmpty();
+
+    await logOutAccount(testBinding.globalStore, eg.selfAccount.id);
+    check(testBinding.globalStore.takeDoRemoveAccountCalls()).single;
+
+    await check(future).throws<AccountNotFoundException>();
+    check(testBinding.globalStore.takeDoRemoveAccountCalls()).isEmpty();
+  }));
+
   // TODO test insertAccount
 
   group('GlobalStore.updateAccount', () {
@@ -824,23 +857,23 @@ void main() {
       checkReload(prepareHandleEventError);
     });
 
-    test('expired queue disposes registered MessageListView instances', () => awaitFakeAsync((async) async {
-      // Regression test for: https://github.com/zulip/zulip-flutter/issues/810
+    test('unexpected poll error, but reload fails with HTTP status code 401; log out', () => awaitFakeAsync((async) async {
       await preparePoll();
 
-      // Make sure there are [MessageListView]s in the message store.
-      MessageListView.init(store: store, narrow: const MentionsNarrow());
-      MessageListView.init(store: store, narrow: const StarredMessagesNarrow());
-      check(store.debugMessageListViews).length.equals(2);
-
-      // Let the server expire the event queue.
-      prepareExpiredEventQueue();
+      prepareUnexpectedLoopError();
       updateMachine.debugAdvanceLoop();
       async.elapse(Duration.zero);
+      check(store).isLoading.isTrue();
+
+      globalStore.loadPerAccountException = ZulipApiException(
+        routeName: '/register', code: 'UNAUTHORIZED', httpStatus: 401,
+        data: {}, message: '');
+      // The reload doesn't happen immediately; there's a timer.
+      check(async.pendingTimers).length.equals(1);
+      async.flushTimers();
 
-      // The old store's [MessageListView]s have been disposed.
-      // (And no exception was thrown; that was #810.)
-      check(store.debugMessageListViews).isEmpty();
+      check(globalStore.takeDoRemoveAccountCalls().single)
+        .equals(eg.selfAccount.id);
     }));
 
     group('report error', () {
@@ -858,7 +891,7 @@ void main() {
 
       Future<void> prepare() async {
         reportErrorToUserBriefly = logReportedError;
-        addTearDown(() => reportErrorToUserBriefly = defaultReportErrorToUserBriefly);
+        addTearDown(() => reportErrorToUserBriefly = reportErrorToConsole);
         await preparePoll(lastEventId: 1);
       }
 
diff --git a/test/model/test_store.dart b/test/model/test_store.dart
index b6887cbed7..534a6003b5 100644
--- a/test/model/test_store.dart
+++ b/test/model/test_store.dart
@@ -129,6 +129,7 @@ class TestGlobalStore extends GlobalStore {
 
   static const Duration removeAccountDuration = Duration(milliseconds: 1);
   Duration? loadPerAccountDuration;
+  Object? loadPerAccountException;
 
   /// Consume the log of calls made to [doRemoveAccount].
   List<int> takeDoRemoveAccountCalls() {
@@ -150,6 +151,9 @@ class TestGlobalStore extends GlobalStore {
     if (loadPerAccountDuration != null) {
       await Future<void>.delayed(loadPerAccountDuration!);
     }
+    if (loadPerAccountException != null) {
+      throw loadPerAccountException!;
+    }
     final initialSnapshot = _initialSnapshots[accountId]!;
     final store = PerAccountStore.fromInitialSnapshot(
       globalStore: this,
diff --git a/test/widgets/actions_test.dart b/test/widgets/actions_test.dart
index 5a957c44e0..d125170258 100644
--- a/test/widgets/actions_test.dart
+++ b/test/widgets/actions_test.dart
@@ -12,6 +12,7 @@ import 'package:zulip/api/model/initial_snapshot.dart';
 import 'package:zulip/api/model/model.dart';
 import 'package:zulip/api/model/narrow.dart';
 import 'package:zulip/api/route/messages.dart';
+import 'package:zulip/model/actions.dart';
 import 'package:zulip/model/localizations.dart';
 import 'package:zulip/model/narrow.dart';
 import 'package:zulip/model/store.dart';
@@ -20,6 +21,7 @@ import 'package:zulip/widgets/actions.dart';
 import 'package:zulip/widgets/app.dart';
 import 'package:zulip/widgets/inbox.dart';
 import 'package:zulip/widgets/page.dart';
+import 'package:zulip/widgets/store.dart';
 
 import '../api/fake_api.dart';
 import '../example_data.dart' as eg;
@@ -109,7 +111,7 @@ void main() {
       final newConnection = separateConnection()
         ..prepare(delay: unregisterDelay, json: {'msg': '', 'result': 'success'});
 
-      final future = logOutAccount(context, eg.selfAccount.id);
+      final future = logOutAccount(GlobalStoreWidget.of(context), eg.selfAccount.id);
       // Unregister-token request and account removal dispatched together
       checkSingleUnregisterRequest(newConnection);
       check(testBinding.globalStore.takeDoRemoveAccountCalls())
@@ -141,7 +143,7 @@ void main() {
       final newConnection = separateConnection()
         ..prepare(delay: unregisterDelay, exception: exception);
 
-      final future = logOutAccount(context, eg.selfAccount.id);
+      final future = logOutAccount(GlobalStoreWidget.of(context), eg.selfAccount.id);
       // Unregister-token request and account removal dispatched together
       checkSingleUnregisterRequest(newConnection);
       check(testBinding.globalStore.takeDoRemoveAccountCalls())
@@ -185,7 +187,7 @@ void main() {
 
       final pushedRoutes = <Route<dynamic>>[];
       testNavObserver.onPushed = (route, prevRoute) => pushedRoutes.add(route);
-      // TODO(#737): switch to a realistic setup:
+      // TODO: switch to a realistic setup:
       //   https://github.com/zulip/zulip-flutter/pull/1076#discussion_r1874124363
       final account1Route = MaterialAccountWidgetRoute(
         accountId: account1.id, page: const InboxPageBody());
@@ -211,7 +213,7 @@ void main() {
       testNavObserver.onRemoved = (route, prevRoute) => removedRoutes.add(route);
 
       final context = tester.element(find.byType(MaterialApp));
-      final future = logOutAccount(context, account1.id);
+      final future = logOutAccount(GlobalStoreWidget.of(context), account1.id);
       await tester.pump(TestGlobalStore.removeAccountDuration);
       await future;
       check(removedRoutes).single.identicalTo(account1Route);
diff --git a/test/widgets/app_test.dart b/test/widgets/app_test.dart
index af386bfdf1..8bceef9c35 100644
--- a/test/widgets/app_test.dart
+++ b/test/widgets/app_test.dart
@@ -3,7 +3,9 @@ import 'dart:async';
 import 'package:checks/checks.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
+import 'package:zulip/api/exception.dart';
 import 'package:zulip/log.dart';
+import 'package:zulip/model/actions.dart';
 import 'package:zulip/model/database.dart';
 import 'package:zulip/widgets/app.dart';
 import 'package:zulip/widgets/home.dart';
@@ -57,6 +59,99 @@ void main() {
     });
   });
 
+  group('_EmptyStackNavigatorObserver', () {
+    late List<Route<void>> pushedRoutes;
+    late List<Route<void>> removedRoutes;
+
+    Future<void> prepare(WidgetTester tester) async {
+      addTearDown(testBinding.reset);
+
+      pushedRoutes = [];
+      removedRoutes = [];
+      final testNavObserver = TestNavigatorObserver();
+      testNavObserver.onPushed = (route, prevRoute) => pushedRoutes.add(route);
+      testNavObserver.onRemoved = (route, prevRoute) => removedRoutes.add(route);
+
+      await tester.pumpWidget(ZulipApp(navigatorObservers: [testNavObserver]));
+      await tester.pump(); // start to load account
+      check(pushedRoutes).single.isA<WidgetRoute>().page.isA<HomePage>();
+      pushedRoutes.clear();
+    }
+
+    testWidgets('do not push route to non-empty navigator stack', (tester) async {
+      const loadPerAccountDuration = Duration(seconds: 30);
+      assert(loadPerAccountDuration > kTryAnotherAccountWaitPeriod);
+      testBinding.globalStore.loadPerAccountDuration = loadPerAccountDuration;
+      testBinding.globalStore.loadPerAccountException = ZulipApiException(
+        routeName: '/register', code: 'UNAUTHORIZED', httpStatus: 401,
+        data: {}, message: '');
+      await testBinding.globalStore.insertAccount(eg.selfAccount.toCompanion(false));
+      await prepare(tester);
+
+      await tester.pump(kTryAnotherAccountWaitPeriod);
+      await tester.tap(find.text('Try another account'));
+      await tester.pump(); // tap the button
+      check(pushedRoutes).single.isA<WidgetRoute>().page.isA<ChooseAccountPage>();
+      pushedRoutes.clear();
+
+      await tester.pump(loadPerAccountDuration); // got the error
+      await tester.pump(TestGlobalStore.removeAccountDuration);
+      check(pushedRoutes).single.isA<DialogRoute<void>>();
+      pushedRoutes.clear();
+      check(removedRoutes).single.isA<WidgetRoute>().page.isA<HomePage>();
+      check(testBinding.globalStore.takeDoRemoveAccountCalls())
+        .single.equals(eg.selfAccount.id);
+
+      await tester.tap(find.byWidget(checkErrorDialog(tester,
+        expectedTitle: 'Could not connect',
+        expectedMessage:
+          'Your account at https://chat.example/ could not be authenticated.'
+          ' Please try logging in again or use another account.')));
+      // No more routes are pushed after dismissing the error dialog,
+      // because the navigator stack was non-empty.
+      check(pushedRoutes).isEmpty();
+    });
+
+    testWidgets('push route when popping last route on stack', (tester) async {
+      testBinding.globalStore.loadPerAccountDuration = Duration.zero;
+      testBinding.globalStore.loadPerAccountException = ZulipApiException(
+        routeName: '/register', code: 'UNAUTHORIZED', httpStatus: 401,
+        data: {}, message: '');
+      await testBinding.globalStore.insertAccount(eg.selfAccount.toCompanion(false));
+      await prepare(tester);
+
+      await tester.pump(Duration.zero); // got the error
+      await tester.pump(TestGlobalStore.removeAccountDuration);
+      check(pushedRoutes).single.isA<DialogRoute<void>>();
+      pushedRoutes.clear();
+      check(removedRoutes).single.isA<WidgetRoute>().page.isA<HomePage>();
+      check(testBinding.globalStore.takeDoRemoveAccountCalls())
+        .single.equals(eg.selfAccount.id);
+
+      await tester.tap(find.byWidget(checkErrorDialog(tester,
+        expectedTitle: 'Could not connect',
+        expectedMessage:
+          'Your account at https://chat.example/ could not be authenticated.'
+          ' Please try logging in again or use another account.')));
+      // The navigator stack became empty after dismissing the error dialog,
+      // so a choose-account page route was pushed.
+      check(pushedRoutes).single.isA<WidgetRoute>().page.isA<ChooseAccountPage>();
+    });
+
+    testWidgets('push route when removing last route on stack', (tester) async {
+      await testBinding.globalStore.add(eg.selfAccount, eg.initialSnapshot());
+      await prepare(tester);
+
+      final future = logOutAccount(testBinding.globalStore, eg.selfAccount.id);
+      await tester.pump(TestGlobalStore.removeAccountDuration);
+      await future;
+      check(pushedRoutes).single.isA<WidgetRoute>().page.isA<ChooseAccountPage>();
+      check(removedRoutes).single.isA<WidgetRoute>().page.isA<HomePage>();
+      check(testBinding.globalStore.takeDoRemoveAccountCalls())
+        .single.equals(eg.selfAccount.id);
+    });
+  });
+
   group('ChooseAccountPage', () {
     Future<void> setupChooseAccountPage(WidgetTester tester, {
       required List<Account> accounts,
@@ -361,5 +456,24 @@ void main() {
       await tester.pumpAndSettle();
       check(findSnackBarByText('unrelated').evaluate()).single;
     });
+
+    testWidgets('reportErrorToUserModally', (tester) async {
+      addTearDown(testBinding.reset);
+      await tester.pumpWidget(const ZulipApp());
+      const message = 'test error message';
+      const details = 'details';
+
+      // Prior to app startup, reportErrorToUserModally only logs.
+      reportErrorToUserModally(message, details: details);
+      check(ZulipApp.ready).value.isFalse();
+      await tester.pump();
+      checkNoErrorDialog(tester);
+
+      check(ZulipApp.ready).value.isTrue();
+      // After app startup, reportErrorToUserModally displays an [AlertDialog].
+      reportErrorToUserModally(message, details: details);
+      await tester.pump();
+      checkErrorDialog(tester, expectedTitle: message, expectedMessage: details);
+    });
   });
 }
diff --git a/test/widgets/home_test.dart b/test/widgets/home_test.dart
index 5bb789727f..15730dc53a 100644
--- a/test/widgets/home_test.dart
+++ b/test/widgets/home_test.dart
@@ -3,10 +3,10 @@ import 'package:flutter/material.dart';
 import 'package:flutter_checks/flutter_checks.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:zulip/api/model/events.dart';
+import 'package:zulip/model/actions.dart';
 import 'package:zulip/model/narrow.dart';
 import 'package:zulip/model/store.dart';
 import 'package:zulip/widgets/about_zulip.dart';
-import 'package:zulip/widgets/actions.dart';
 import 'package:zulip/widgets/app.dart';
 import 'package:zulip/widgets/app_bar.dart';
 import 'package:zulip/widgets/home.dart';
@@ -15,6 +15,7 @@ import 'package:zulip/widgets/inbox.dart';
 import 'package:zulip/widgets/message_list.dart';
 import 'package:zulip/widgets/page.dart';
 import 'package:zulip/widgets/profile.dart';
+import 'package:zulip/widgets/store.dart';
 import 'package:zulip/widgets/subscription_list.dart';
 import 'package:zulip/widgets/theme.dart';
 
@@ -454,7 +455,7 @@ void main () {
     checkOnLoadingPage();
 
     final element = tester.element(find.byType(MaterialApp));
-    final future = logOutAccount(element, eg.selfAccount.id);
+    final future = logOutAccount(GlobalStoreWidget.of(element), eg.selfAccount.id);
     await tester.pump(TestGlobalStore.removeAccountDuration);
     await future;
     // No error expected from briefly not having
@@ -472,7 +473,7 @@ void main () {
     checkOnHomePage(tester, expectedAccount: eg.selfAccount);
 
     final element = tester.element(find.byType(HomePage));
-    final future = logOutAccount(element, eg.selfAccount.id);
+    final future = logOutAccount(GlobalStoreWidget.of(element), eg.selfAccount.id);
     await tester.pump(TestGlobalStore.removeAccountDuration);
     await future;
     // No error expected from briefly not having
diff --git a/test/widgets/message_list_test.dart b/test/widgets/message_list_test.dart
index b3cc208463..204993cc76 100644
--- a/test/widgets/message_list_test.dart
+++ b/test/widgets/message_list_test.dart
@@ -12,6 +12,7 @@ import 'package:zulip/api/model/initial_snapshot.dart';
 import 'package:zulip/api/model/model.dart';
 import 'package:zulip/api/model/narrow.dart';
 import 'package:zulip/api/route/messages.dart';
+import 'package:zulip/model/actions.dart';
 import 'package:zulip/model/localizations.dart';
 import 'package:zulip/model/narrow.dart';
 import 'package:zulip/model/store.dart';
@@ -130,6 +131,26 @@ void main() {
       final state = MessageListPage.ancestorOf(tester.element(find.text("a message")));
       check(state.composeBoxController).isNull();
     });
+
+    testWidgets('dispose MessageListView when logged out', (tester) async {
+      addTearDown(testBinding.reset);
+      await testBinding.globalStore.add(eg.selfAccount, eg.initialSnapshot());
+      store = await testBinding.globalStore.perAccount(eg.selfAccount.id);
+      (store.connection as FakeApiConnection).prepare(json: eg.newestGetMessagesResult(
+        foundOldest: true, messages: [eg.streamMessage()]).toJson());
+      await tester.pumpWidget(TestZulipApp(
+        accountId: eg.selfAccount.id,
+        skipAssertAccountExists: true,
+        child: MessageListPage(initNarrow: const CombinedFeedNarrow())));
+      await tester.pump();
+      await tester.pump();
+      check(store.debugMessageListViews).single;
+
+      final future = logOutAccount(testBinding.globalStore, eg.selfAccount.id);
+      await tester.pump(TestGlobalStore.removeAccountDuration);
+      await future;
+      check(store.debugMessageListViews).isEmpty();
+    });
   });
 
   group('app bar', () {