[Firebase_core]: Android Firestore initialization fails on second launch with ConcurrentModificationException

[MERCURY-76]

Is there an existing issue for this?

• I have searched the existing issues.

Which plugins are affected?

Core

Which platforms are affected?

Android

Description

When running the app in debug mode on Android, the first launch works correctly and both Firestore databases are initialized as expected.
However, when I hot restart or relaunch the app in debug mode (while the previous debug session is still active), a PlatformException occurs during Firebase initialization with the following error:

java.util.ConcurrentModificationException
...
Caused by: java.util.ConcurrentModificationException
at io.flutter.plugins.firebase.firestore.FlutterFirebaseFirestorePlugin.lambda$didReinitializeFirebaseCore$1

The issue seems to happen when the app tries to reinitialize multiple Firestore instances for the same FirebaseApp.

Here’s a simplified version of the initialization code:

Future initialize() async {
try {
final app = Firebase.app();

final mainFirestore = FirebaseFirestore.instanceFor(
  app: app,
  databaseId: AppService.shared.config.databaseId,
);

mainFirestore.settings = const Settings(
  persistenceEnabled: true,
  cacheSizeBytes: Settings.CACHE_SIZE_UNLIMITED,
);

final appConfig = FirebaseFirestore.instanceFor(
  app: app,
  databaseId: "app-config",
);

appConfig.settings = const Settings(
  persistenceEnabled: true,
  cacheSizeBytes: Settings.CACHE_SIZE_UNLIMITED,
);

firestore = mainFirestore;
appConfigFirestore = appConfig;

logger.i('[FirestoreService] Initialization completed');

} catch (e) {
logger.e('[FirestoreService] Error during initialization: $e');
rethrow;
}
}

This method is called after:

await Firebase.initializeApp(options: DefaultFirebaseOptions.currentPlatform);

Expected behavior:
Both Firestore instances (mainFirestore and appConfigFirestore) should initialize successfully on every app launch.

Actual behavior:
On the second launch in debug (or after a hot restart), the app crashes with a ConcurrentModificationException originating from Firebase Core or Firestore plugin internals.
It seems that the Firestore plugin tries to reinitialize its internal registry while multiple instances are being set up concurrently.

Reproducing the issue

import 'package:flutter/material.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'firebase_options.dart';

class FirestoreService {
late FirebaseFirestore firestore;
late FirebaseFirestore appConfigFirestore;

Future initialize() async {
try {
final app = Firebase.app();

  final mainFirestore = FirebaseFirestore.instanceFor(
    app: app,
    databaseId: 'main-db',
  );

  mainFirestore.settings = const Settings(
    persistenceEnabled: true,
    cacheSizeBytes: Settings.CACHE_SIZE_UNLIMITED,
  );

  final appConfig = FirebaseFirestore.instanceFor(
    app: app,
    databaseId: 'app-config',
  );

  appConfig.settings = const Settings(
    persistenceEnabled: true,
    cacheSizeBytes: Settings.CACHE_SIZE_UNLIMITED,
  );

  firestore = mainFirestore;
  appConfigFirestore = appConfig;

  print('[FirestoreService] Initialization completed');
} catch (e) {
  print('[FirestoreService] Error during initialization: $e');
  rethrow;
}

}
}

Future main() async {
WidgetsFlutterBinding.ensureInitialized();
await Firebase.initializeApp(options: DefaultFirebaseOptions.currentPlatform);
await FirestoreService().initialize();
runApp(const MyApp());
}

class MyApp extends StatelessWidget {
const MyApp({super.key});

@OverRide
Widget build(BuildContext context) {
return const MaterialApp(
home: Scaffold(
body: Center(
child: Text('Firestore multi-instance test'),
),
),
);
}
}

Firebase Core version

4.2.0

Flutter Version

3.32.8

Relevant Log Output

>  [ERROR:flutter/runtime/dart_vm_initializer.cc(40)] Unhandled Exception: PlatformException(java.util.concurrent.ExecutionException: java.util.concurrent.ExecutionException: java.util.ConcurrentModificationException, ExecutionException, Cause: java.util.concurrent.ExecutionException: java.util.ConcurrentModificationException, Stacktrace: java.util.concurrent.ExecutionException: java.util.concurrent.ExecutionException: java.util.ConcurrentModificationException
> E/flutter (18312): 	at com.google.android.gms.tasks.Tasks.zza(com.google.android.gms:play-services-tasks@@18.3.2:5)
> E/flutter (18312): 	at com.google.android.gms.tasks.Tasks.await(com.google.android.gms:play-services-tasks@@18.3.2:9)
> E/flutter (18312): 	at io.flutter.plugins.firebase.core.FlutterFirebaseCorePlugin.lambda$initializeCore$4(FlutterFirebaseCorePlugin.java:190)
> E/flutter (18312): 	at io.flutter.plugins.firebase.core.FlutterFirebaseCorePlugin.$r8$lambda$NxDsUkqe93KkHUjQxhXhbVz2y_4(Unknown Source:0)
> E/flutter (18312): 	at io.flutter.plugins.firebase.core.FlutterFirebaseCorePlugin$$ExternalSyntheticLambda7.run(D8$$SyntheticClass:0)
> E/flutter (18312): 	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1156)
> E/flutter (18312): 	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:651)
> E/flutter (18312): 	at java.lang.Thread.run(Thread.java:1119)
> E/flutter (18312): Caused by: java.util.concurrent.ExecutionException: java.util.ConcurrentModificationException
> E/flutter (18312): 	at com.google.android.gms.tasks.Tasks.zza(com.google.android.gms:play-services-tasks@@18.3.2:5)
> E/flutter (18312): 	at com.google.android.gms.tasks.Tasks.await(com.google.android.gms:play-services-tasks@@18.3.2:9)
> E/flutter (18312): 	at io.flutter.plugins.firebase.core.FlutterFirebasePluginRegistry.lambda$didReinitializeFirebaseCore$1(FlutterFirebasePluginRegistry.java:82)
> E/flutter (18312): 	at io.flutter.plugins.firebase.core.FlutterFirebasePluginRegistry$$ExternalSyntheticLambda0.run(D8$$SyntheticClass:0)
> E/flutter (18312): 	... 3 more
> E/flutter (18312): Caused by: java.util.ConcurrentModificationException
> E/flutter (18312): 	at java.util.HashMap$HashIterator.nextNode(HashMap.java:1603)
> E/flutter (18312): 	at java.util.HashMap$EntryIterator.next(HashMap.java:1636)
> E/flutter (18312): 	at java.util.HashMap$EntryIterator.next(HashMap.java:1634)
> E/flutter (18312): 	at io.flutter.plugins.firebase.firestore.FlutterFirebaseFirestorePlugin.lambda$didReinitializeFirebaseCore$1(FlutterFirebaseFirestorePlugin.java:207)
> E/flutter (18312): 	at io.flutter.plugins.firebase.firestore.FlutterFirebaseFirestorePlugin.$r8$lambda$LWPUzGoM67fJ0VnXoPogtvBOysE(Unknown Source:0)
> E/flutter (18312): 	at io.flutter.plugins.firebase.firestore.FlutterFirebaseFirestorePlugin$$ExternalSyntheticLambda5.run(D8$$SyntheticClass:0)
> E/flutter (18312): 	... 3 more
> E/flutter (18312): , null)
> E/flutter (18312): #0      FirebaseCoreHostApi.initializeCore (package:firebase_core_platform_interface/src/pigeon/messages.pigeon.dart:303:7)
> E/flutter (18312): <asynchronous suspension>
> E/flutter (18312): #1      MethodChannelFirebase._initializeCore (package:firebase_core_platform_interface/src/method_channel/method_channel_firebase.dart:29:41)
> E/flutter (18312): <asynchronous suspension>
> E/flutter (18312): #2      MethodChannelFirebase.initializeApp (package:firebase_core_platform_interface/src/method_channel/method_channel_firebase.dart:70:7)
> E/flutter (18312): <asynchronous suspension>
> E/flutter (18312): #3      Firebase.initializeApp (package:firebase_core/src/firebase.dart:78:31)
> E/flutter (18312): <asynchronous suspension>
> E/flutter (18312): #4      runMainApp (package:myterritory/main.dart:20:3)
> E/flutter (18312): <asynchronous suspension>
> E/flutter (18312):

Flutter dependencies

Expand Flutter dependencies snippet

Dart SDK 3.8.1
Flutter SDK 3.32.8

dependencies:
- alert_info 0.0.6 [flutter]
- amazing_icons 3.0.1 [flutter jovial_svg]
- animated_segmented_tab_control 2.0.0 [flutter]
- app_badge_plus 1.2.3 [flutter plugin_platform_interface]
- app_links 6.4.1 [flutter app_links_linux app_links_platform_interface app_links_web]
- app_tracking_transparency 2.0.6+1 [flutter]
- build_runner 2.7.1 [args async build build_config build_daemon build_runner_core built_collection code_builder crypto dart_style frontend_server_client glob graphs http_multi_server io logging meta mime path pub_semver shelf shelf_web_socket stack_trace stream_transform watcher web_socket_channel yaml]
- carousel_slider 5.1.1 [flutter]
- cloud_firestore 6.0.3 [cloud_firestore_platform_interface cloud_firestore_web collection firebase_core firebase_core_platform_interface flutter meta]
- collection 1.19.1
- connectivity_plus 7.0.0 [flutter flutter_web_plugins connectivity_plus_platform_interface web meta nm collection]
- csv 6.0.0
- device_info_plus 12.2.0 [device_info_plus_platform_interface ffi file flutter flutter_web_plugins meta web win32 win32_registry]
- dio 5.9.0 [async collection http_parser meta mime path dio_web_adapter]
- dismiss_keyboard_on_tap 2.0.1 [flutter]
- extended_image 10.0.1 [extended_image_library flutter meta vector_math]
- file_picker 10.3.3 [flutter flutter_web_plugins flutter_plugin_android_lifecycle plugin_platform_interface ffi path win32 cross_file web dbus]
- firebase_analytics 12.0.3 [firebase_analytics_platform_interface firebase_analytics_web firebase_core firebase_core_platform_interface flutter]
- firebase_auth 6.1.1 [firebase_auth_platform_interface firebase_auth_web firebase_core firebase_core_platform_interface flutter meta]
- firebase_core 4.2.0 [firebase_core_platform_interface firebase_core_web flutter meta]
- firebase_crashlytics 5.0.3 [firebase_core firebase_core_platform_interface firebase_crashlytics_platform_interface flutter stack_trace]
- firebase_messaging 16.0.3 [firebase_core firebase_core_platform_interface firebase_messaging_platform_interface firebase_messaging_web flutter meta]
- firebase_storage 13.0.3 [firebase_core firebase_core_platform_interface firebase_storage_platform_interface firebase_storage_web flutter]
- fl_chart 1.0.0 [equatable flutter vector_math]
- flutter 0.0.0 [characters collection material_color_utilities meta vector_math sky_engine]
- flutter_animate 4.5.2 [flutter flutter_shaders]
- flutter_cached_pdfview 0.4.3 [flutter flutter_pdfview flutter_cache_manager path_provider path]
- flutter_datetime_picker_plus 2.2.0 [flutter]
- flutter_google_places_sdk 0.4.2+1 [flutter flutter_google_places_sdk_platform_interface flutter_google_places_sdk_ios flutter_google_places_sdk_web flutter_google_places_sdk_android flutter_google_places_sdk_windows flutter_google_places_sdk_linux flutter_google_places_sdk_macos]
- flutter_image_compress 2.4.0 [flutter flutter_image_compress_platform_interface flutter_image_compress_common flutter_image_compress_web flutter_image_compress_macos flutter_image_compress_ohos]
- flutter_inappwebview 6.1.5 [flutter flutter_inappwebview_platform_interface flutter_inappwebview_android flutter_inappwebview_ios flutter_inappwebview_macos flutter_inappwebview_web flutter_inappwebview_windows]
- flutter_keyboard_visibility 6.0.0 [meta flutter_keyboard_visibility_platform_interface flutter_keyboard_visibility_linux flutter_keyboard_visibility_macos flutter_keyboard_visibility_web flutter_keyboard_visibility_windows flutter]
- flutter_local_notifications 19.5.0 [clock flutter flutter_local_notifications_linux flutter_local_notifications_windows flutter_local_notifications_platform_interface timezone]
- flutter_localizations 0.0.0 [flutter intl characters clock collection material_color_utilities meta path vector_math]
- flutter_pdfview 1.4.3 [flutter]
- flutter_polyline_points 3.1.0 [flutter http]
- flutter_svg 2.2.1 [flutter http vector_graphics vector_graphics_codec vector_graphics_compiler]
- flutter_switch 0.3.2 [flutter]
- geocoding 4.0.0 [flutter geocoding_platform_interface geocoding_android geocoding_ios]
- geolocator 14.0.2 [flutter geolocator_platform_interface geolocator_android geolocator_apple geolocator_web geolocator_windows geolocator_linux]
- get 5.0.0-release-candidate-9.3.2 [flutter flutter_web_plugins web]
- google_maps_cluster_manager_2 3.2.0 [flutter google_maps_flutter_platform_interface]
- google_maps_flutter 2.13.1 [flutter google_maps_flutter_android google_maps_flutter_ios google_maps_flutter_platform_interface google_maps_flutter_web]
- google_sign_in 7.2.0 [flutter google_sign_in_android google_sign_in_ios google_sign_in_platform_interface google_sign_in_web]
- grouped_list 6.0.0 [flutter]
- http 1.5.0 [async http_parser meta web]
- hugeicons 1.1.1 [flutter flutter_svg]
- in_app_review 2.0.11 [flutter in_app_review_platform_interface]
- intl 0.20.2 [clock meta path]
- ionicons 0.2.2 [flutter]
- isar_community 3.3.0-dev.3 [ffi js meta]
- isar_community_flutter_libs 3.3.0-dev.3 [flutter isar_community]
- location 8.0.1 [flutter location_platform_interface location_web]
- logger 2.6.2 [meta]
- lottie 3.3.1 [archive flutter http path vector_math]
- lucide_icons_flutter 3.1.5 [flutter]
- map_launcher 4.4.2 [flutter plugin_platform_interface]
- mobile_scanner 7.1.3 [collection flutter flutter_web_plugins meta plugin_platform_interface web]
- package_info_plus 8.3.1 [ffi flutter flutter_web_plugins http meta path package_info_plus_platform_interface web win32 clock]                                                                                       
- path_provider 2.1.5 [flutter path_provider_android path_provider_foundation path_provider_linux path_provider_platform_interface path_provider_windows]                                                             
- pdf 3.11.3 [archive barcode bidi crypto image meta path_parsing vector_math xml]
- permission_handler 12.0.1 [flutter meta permission_handler_android permission_handler_apple permission_handler_html permission_handler_windows permission_handler_platform_interface]                               
- qr_flutter 4.1.0 [flutter qr]
- screen_brightness 2.1.7 [flutter screen_brightness_platform_interface screen_brightness_android screen_brightness_ios screen_brightness_macos screen_brightness_windows screen_brightness_ohos]                     
- share_plus 12.0.1 [cross_file meta mime flutter flutter_web_plugins share_plus_platform_interface file url_launcher_web url_launcher_windows url_launcher_linux url_launcher_platform_interface ffi web win32]      
- shared_preferences 2.5.3 [flutter shared_preferences_android shared_preferences_foundation shared_preferences_linux shared_preferences_platform_interface shared_preferences_web shared_preferences_windows]        
- sign_in_with_apple 7.0.1 [flutter meta sign_in_with_apple_platform_interface sign_in_with_apple_web]
- smooth_page_indicator 1.2.1 [flutter]
- smooth_sheets2 0.10.0 [collection flutter meta]
- top_snackbar_flutter 3.3.0 [flutter]
- tutorial_coach_mark 1.3.3 [flutter]
- url_launcher 6.3.2 [flutter url_launcher_android url_launcher_ios url_launcher_linux url_launcher_macos url_launcher_platform_interface url_launcher_web url_launcher_windows]                                      
- uuid 4.5.1 [crypto sprintf meta fixnum]
- video_player 2.10.0 [flutter html video_player_android video_player_avfoundation video_player_platform_interface video_player_web]                                                                                  
- xml 6.6.1 [collection meta petitparser]

dev dependencies:
- flutter_lints 6.0.0 [lints]
- flutter_test 0.0.0 [flutter test_api matcher path fake_async clock stack_trace vector_math leak_tracker_flutter_testing async boolean_selector characters collection leak_tracker leak_tracker_testing material_color_utilities meta source_span stream_channel string_scanner term_glyph vm_service]                          
- isar_community_generator 3.3.0-dev.3 [analyzer build dart_style dartx glob isar_community path source_gen xxh3]                                                                                                     

transitive dependencies:
- _fe_analyzer_shared 88.0.0 [meta]
- _flutterfire_internals 1.3.63 [collection firebase_core firebase_core_platform_interface flutter meta]
- analyzer 8.1.1 [_fe_analyzer_shared collection convert crypto glob meta package_config path pub_semver source_span watcher yaml]                                                                                    
- app_links_linux 1.0.3 [flutter app_links_platform_interface gtk]
- app_links_platform_interface 2.0.2 [flutter plugin_platform_interface]
- app_links_web 1.0.4 [flutter flutter_web_plugins app_links_platform_interface web]
- archive 4.0.7 [crypto path posix]
- args 2.7.0
- async 2.13.0 [collection meta]
- barcode 2.2.9 [meta qr]
- bidi 2.0.13
- boolean_selector 2.1.2 [source_span string_scanner]
- build 3.1.0 [analyzer async build_runner_core convert crypto glob logging package_config path]
- build_config 1.2.0 [checked_yaml json_annotation path pubspec_parse]
- build_daemon 4.0.4 [built_collection built_value crypto http_multi_server logging path pool shelf shelf_web_socket stream_transform watcher web_socket_channel]                                                     
- build_resolvers 3.0.3 [analyzer async build build_runner_core collection package_config path pool pub_semver]                                                                                                       
- build_runner_core 9.3.1 [analyzer async build build_config build_resolvers build_runner built_collection built_value collection convert crypto glob graphs json_annotation logging meta package_config path pool timing watcher yaml]                                                                                          
- built_collection 5.1.1
- built_value 8.12.0 [built_collection collection fixnum meta]
- characters 1.4.0
- checked_yaml 2.0.4 [json_annotation source_span yaml]
- clock 1.1.2
- cloud_firestore_platform_interface 7.0.3 [_flutterfire_internals collection firebase_core flutter meta plugin_platform_interface]                                                                                   
- cloud_firestore_web 5.0.3 [_flutterfire_internals cloud_firestore_platform_interface collection firebase_core firebase_core_web flutter flutter_web_plugins]                                                        
- code_builder 4.11.0 [built_collection built_value collection matcher meta]
- connectivity_plus_platform_interface 2.0.1 [flutter meta plugin_platform_interface]
- convert 3.1.2 [typed_data]
- cross_file 0.3.4+2 [meta web]
- crypto 3.0.6 [typed_data]
- csslib 1.0.2 [source_span]
- dart_style 3.1.2 [analyzer args collection package_config path pub_semver source_span yaml]
- dartx 1.2.0 [characters collection crypto meta path time]
- dbus 0.7.11 [args ffi meta xml]
- device_info_plus_platform_interface 7.0.3 [flutter meta plugin_platform_interface]
- dio_web_adapter 2.1.1 [dio http_parser meta web]
- equatable 2.0.7 [collection meta]
- extended_image_library 5.0.1 [crypto flutter http_client_helper js path path_provider web]
- fake_async 1.3.3 [clock collection]
- ffi 2.1.4
- file 7.0.1 [meta path]
- firebase_analytics_platform_interface 5.0.3 [_flutterfire_internals firebase_core flutter meta plugin_platform_interface]                                                                                           
- firebase_analytics_web 0.6.0+3 [_flutterfire_internals firebase_analytics_platform_interface firebase_core firebase_core_web flutter flutter_web_plugins]                                                           
- firebase_auth_platform_interface 8.1.3 [_flutterfire_internals collection firebase_core flutter http meta plugin_platform_interface]                                                                                
- firebase_auth_web 6.0.4 [firebase_auth_platform_interface firebase_core firebase_core_web flutter flutter_web_plugins http_parser meta web]                                                                         
- firebase_core_platform_interface 6.0.2 [collection flutter flutter_test meta plugin_platform_interface]
- firebase_core_web 3.2.0 [firebase_core_platform_interface flutter flutter_web_plugins meta web]
- firebase_crashlytics_platform_interface 3.8.14 [_flutterfire_internals collection firebase_core flutter meta plugin_platform_interface]                                                                             
- firebase_messaging_platform_interface 4.7.3 [_flutterfire_internals firebase_core flutter meta plugin_platform_interface]                                                                                           
- firebase_messaging_web 4.0.3 [_flutterfire_internals firebase_core firebase_core_web firebase_messaging_platform_interface flutter flutter_web_plugins meta web]                                                    
- firebase_storage_platform_interface 5.2.14 [_flutterfire_internals collection firebase_core flutter meta plugin_platform_interface]                                                                                 
- firebase_storage_web 3.10.21 [_flutterfire_internals async firebase_core firebase_core_web firebase_storage_platform_interface flutter flutter_web_plugins http meta web]                                           
- fixnum 1.1.1
- flutter_cache_manager 3.4.1 [clock collection file flutter http path path_provider rxdart sqflite uuid]
- flutter_google_places_sdk_android 0.2.0 [flutter flutter_google_places_sdk_platform_interface]
- flutter_google_places_sdk_http 0.2.1 [flutter http latlong2 flutter_google_places_sdk_platform_interface freezed_annotation json_annotation]                                                                        
- flutter_google_places_sdk_ios 0.2.0 [flutter flutter_google_places_sdk_platform_interface]
- flutter_google_places_sdk_linux 0.2.1 [flutter flutter_google_places_sdk_platform_interface flutter_google_places_sdk_http]                                                                                         
- flutter_google_places_sdk_macos 0.2.1 [flutter flutter_google_places_sdk_platform_interface flutter_google_places_sdk_http]                                                                                         
- flutter_google_places_sdk_platform_interface 0.3.2+1 [flutter freezed_annotation json_annotation plugin_platform_interface]                                                                                         
- flutter_google_places_sdk_web 0.2.0 [flutter flutter_web_plugins flutter_google_places_sdk_platform_interface google_maps collection web]                                                                           
- flutter_google_places_sdk_windows 0.2.1 [flutter flutter_google_places_sdk_platform_interface flutter_google_places_sdk_http]                                                                                       
- flutter_image_compress_common 1.0.6 [flutter flutter_image_compress_platform_interface]
- flutter_image_compress_macos 1.0.3 [flutter flutter_image_compress_platform_interface]
- flutter_image_compress_ohos 0.0.3 [flutter flutter_image_compress_platform_interface]
- flutter_image_compress_platform_interface 1.0.5 [flutter plugin_platform_interface cross_file]
- flutter_image_compress_web 0.1.5 [flutter flutter_web_plugins flutter_image_compress_platform_interface web]                                                                                                        
- flutter_inappwebview_android 1.1.3 [flutter flutter_inappwebview_platform_interface]
- flutter_inappwebview_internal_annotations 1.2.0
- flutter_inappwebview_ios 1.1.2 [flutter flutter_inappwebview_platform_interface]
- flutter_inappwebview_macos 1.1.2 [flutter flutter_inappwebview_platform_interface]
- flutter_inappwebview_platform_interface 1.3.0+1 [flutter flutter_inappwebview_internal_annotations plugin_platform_interface]                                                                                       
- flutter_inappwebview_web 1.1.2 [flutter flutter_web_plugins web flutter_inappwebview_platform_interface]
- flutter_inappwebview_windows 0.6.0 [flutter flutter_inappwebview_platform_interface]
- flutter_keyboard_visibility_linux 1.0.0 [flutter_keyboard_visibility_platform_interface flutter]
- flutter_keyboard_visibility_macos 1.0.0 [flutter_keyboard_visibility_platform_interface flutter]
- flutter_keyboard_visibility_platform_interface 2.0.0 [flutter meta plugin_platform_interface]
- flutter_keyboard_visibility_web 2.0.0 [flutter_keyboard_visibility_platform_interface flutter_web_plugins flutter]                                                                                                  
- flutter_keyboard_visibility_windows 1.0.0 [flutter_keyboard_visibility_platform_interface flutter]
- flutter_local_notifications_linux 6.0.0 [dbus ffi flutter flutter_local_notifications_platform_interface path xdg_directories]                                                                                      
- flutter_local_notifications_platform_interface 9.1.0 [plugin_platform_interface]
- flutter_local_notifications_windows 1.0.3 [flutter ffi flutter_local_notifications_platform_interface meta timezone xml]                                                                                            
- flutter_plugin_android_lifecycle 2.0.30 [flutter]
- flutter_shaders 0.1.3 [flutter vector_math]
- flutter_web_plugins 0.0.0 [flutter characters collection material_color_utilities meta vector_math]
- freezed_annotation 3.1.0 [collection json_annotation meta]
- frontend_server_client 4.0.0 [async path]
- geoclue 0.1.1 [dbus meta]
- geocoding_android 4.0.1 [flutter geocoding_platform_interface]
- geocoding_ios 3.1.0 [flutter geocoding_platform_interface]
- geocoding_platform_interface 3.2.0 [flutter meta plugin_platform_interface]
- geolocator_android 5.0.2 [flutter geolocator_platform_interface meta uuid]
- geolocator_apple 2.3.13 [flutter geolocator_platform_interface]
- geolocator_linux 0.2.3 [dbus flutter geoclue geolocator_platform_interface gsettings package_info_plus]
- geolocator_platform_interface 4.2.6 [flutter plugin_platform_interface vector_math meta]
- geolocator_web 4.1.3 [flutter flutter_web_plugins geolocator_platform_interface web]
- geolocator_windows 0.2.5 [flutter geolocator_platform_interface]
- glob 2.1.3 [async collection file path string_scanner]
- google_identity_services_web 0.3.3+1 [meta web]
- google_maps 8.2.0 [meta web]
- google_maps_flutter_android 2.18.2 [flutter flutter_plugin_android_lifecycle google_maps_flutter_platform_interface stream_transform]                                                                               
- google_maps_flutter_ios 2.15.5 [flutter google_maps_flutter_platform_interface stream_transform]
- google_maps_flutter_platform_interface 2.14.0 [collection flutter plugin_platform_interface stream_transform]                                                                                                       
- google_maps_flutter_web 0.5.14+2 [collection flutter flutter_web_plugins google_maps google_maps_flutter_platform_interface sanitize_html stream_transform web]                                                     
- google_sign_in_android 7.2.0 [flutter google_sign_in_platform_interface]
- google_sign_in_ios 6.2.1 [flutter google_sign_in_platform_interface]
- google_sign_in_platform_interface 3.1.0 [flutter plugin_platform_interface]
- google_sign_in_web 1.1.0 [flutter flutter_web_plugins google_identity_services_web google_sign_in_platform_interface http web]                                                                                      
- graphs 2.3.2 [collection]
- gsettings 0.2.8 [dbus xdg_directories]
- gtk 2.1.0 [ffi flutter meta]
- html 0.15.6 [csslib source_span]
- http_client_helper 3.0.0 [http]
- http_multi_server 3.2.2 [async]
- http_parser 4.1.2 [collection source_span string_scanner typed_data]
- image 4.5.4 [archive meta xml]
- in_app_review_platform_interface 2.0.5 [flutter url_launcher plugin_platform_interface platform]
- io 1.0.5 [meta path string_scanner]
- jovial_misc 0.9.2 [async collection convert meta]
- jovial_svg 1.1.28 [xml collection args vector_math jovial_misc http meta flutter]
- js 0.7.2
- json_annotation 4.9.0 [meta]
- latlong2 0.9.1 [intl]
- leak_tracker 10.0.9 [clock collection meta path vm_service]
- leak_tracker_flutter_testing 3.0.9 [flutter leak_tracker leak_tracker_testing matcher meta]
- leak_tracker_testing 3.0.1 [leak_tracker matcher meta]
- lints 6.0.0
- location_platform_interface 6.0.1 [flutter plugin_platform_interface]
- location_web 6.0.1 [flutter flutter_web_plugins http_parser location_platform_interface web]
- logging 1.3.0
- matcher 0.12.17 [async meta stack_trace term_glyph test_api]
- material_color_utilities 0.11.1 [collection]
- meta 1.16.0
- mime 2.0.0
- nm 0.5.0 [dbus]
- package_config 2.2.0 [path]
- package_info_plus_platform_interface 3.2.1 [flutter meta plugin_platform_interface]
- path 1.9.1
- path_parsing 1.1.0 [meta vector_math]
- path_provider_android 2.2.18 [flutter path_provider_platform_interface]
- path_provider_foundation 2.4.2 [flutter path_provider_platform_interface]
- path_provider_linux 2.2.1 [ffi flutter path path_provider_platform_interface xdg_directories]
- path_provider_platform_interface 2.1.2 [flutter platform plugin_platform_interface]
- path_provider_windows 2.3.0 [ffi flutter path path_provider_platform_interface]
- permission_handler_android 13.0.1 [flutter permission_handler_platform_interface]
- permission_handler_apple 9.4.7 [flutter permission_handler_platform_interface]
- permission_handler_html 0.1.3+5 [flutter flutter_web_plugins permission_handler_platform_interface web]
- permission_handler_platform_interface 4.3.0 [flutter meta plugin_platform_interface]
- permission_handler_windows 0.2.1 [flutter permission_handler_platform_interface]
- petitparser 7.0.1 [meta collection]
- platform 3.1.6
- plugin_platform_interface 2.1.8 [meta]
- pool 1.5.2 [async stack_trace]
- posix 6.0.3 [ffi meta path]
- pub_semver 2.2.0 [collection]
- pubspec_parse 1.5.0 [checked_yaml collection json_annotation pub_semver yaml]
- qr 3.0.2 [meta]
- rxdart 0.28.0
- sanitize_html 2.1.0 [html meta]
- screen_brightness_android 2.1.3 [flutter screen_brightness_platform_interface]
- screen_brightness_ios 2.1.2 [flutter screen_brightness_platform_interface]
- screen_brightness_macos 2.1.1 [flutter screen_brightness_platform_interface]
- screen_brightness_ohos 2.1.2 [flutter screen_brightness_platform_interface]
- screen_brightness_platform_interface 2.1.0 [flutter plugin_platform_interface]
- screen_brightness_windows 2.1.0 [flutter screen_brightness_platform_interface]
- share_plus_platform_interface 6.1.0 [cross_file flutter meta mime plugin_platform_interface path_provider uuid]                                                                                                     
- shared_preferences_android 2.4.13 [flutter shared_preferences_platform_interface]
- shared_preferences_foundation 2.5.4 [flutter shared_preferences_platform_interface]
- shared_preferences_linux 2.4.1 [file flutter path path_provider_linux path_provider_platform_interface shared_preferences_platform_interface]                                                                       
- shared_preferences_platform_interface 2.4.1 [flutter plugin_platform_interface]
- shared_preferences_web 2.4.3 [flutter flutter_web_plugins shared_preferences_platform_interface web]
- shared_preferences_windows 2.4.1 [file flutter path path_provider_platform_interface path_provider_windows shared_preferences_platform_interface]                                                                   
- shelf 1.4.2 [async collection http_parser path stack_trace stream_channel]
- shelf_web_socket 3.0.0 [shelf stream_channel web_socket_channel]
- sign_in_with_apple_platform_interface 2.0.0 [flutter plugin_platform_interface meta]
- sign_in_with_apple_web 3.0.0 [flutter flutter_web_plugins sign_in_with_apple_platform_interface]
- sky_engine 0.0.0
- source_gen 3.1.0 [analyzer async build dart_style glob path pub_semver source_span yaml]
- source_span 1.10.1 [collection path term_glyph]
- sprintf 7.0.0
- sqflite 2.4.2 [flutter sqflite_android sqflite_darwin sqflite_platform_interface sqflite_common path]
- sqflite_android 2.4.1 [flutter sqflite_common path sqflite_platform_interface]
- sqflite_common 2.5.6 [synchronized path meta]
- sqflite_darwin 2.4.2 [flutter sqflite_platform_interface meta sqflite_common path]
- sqflite_platform_interface 2.4.0 [flutter platform sqflite_common plugin_platform_interface meta]
- stack_trace 1.12.1 [path]
- stream_channel 2.1.4 [async]
- stream_transform 2.1.1
- string_scanner 1.4.1 [source_span]
- synchronized 3.4.0
- term_glyph 1.2.2
- test_api 0.7.4 [async boolean_selector collection meta source_span stack_trace stream_channel string_scanner term_glyph]                                                                                            
- time 2.1.5 [clock]
- timezone 0.10.1 [http path]
- timing 1.0.2 [json_annotation]
- typed_data 1.4.0 [collection]
- url_launcher_android 6.3.20 [flutter url_launcher_platform_interface]
- url_launcher_ios 6.3.4 [flutter url_launcher_platform_interface]
- url_launcher_linux 3.2.1 [flutter url_launcher_platform_interface]
- url_launcher_macos 3.2.3 [flutter url_launcher_platform_interface]
- url_launcher_platform_interface 2.3.2 [flutter plugin_platform_interface]
- url_launcher_web 2.4.1 [flutter flutter_web_plugins url_launcher_platform_interface web]
- url_launcher_windows 3.1.4 [flutter url_launcher_platform_interface]
- vector_graphics 1.1.19 [flutter http vector_graphics_codec]
- vector_graphics_codec 1.1.13
- vector_graphics_compiler 1.1.19 [args meta path path_parsing vector_graphics_codec xml]
- vector_math 2.1.4
- video_player_android 2.8.14 [flutter video_player_platform_interface]
- video_player_avfoundation 2.8.4 [flutter video_player_platform_interface]
- video_player_platform_interface 6.4.0 [flutter plugin_platform_interface]
- video_player_web 2.4.0 [flutter flutter_web_plugins video_player_platform_interface web]
- vm_service 15.0.0
- watcher 1.1.4 [async path]
- web 1.1.1
- web_socket 1.0.1 [web]
- web_socket_channel 3.0.3 [async crypto stream_channel web web_socket]
- win32 5.14.0 [ffi]
- win32_registry 2.1.0 [ffi meta win32]
- xdg_directories 1.1.0 [meta path]
- xxh3 1.2.0
- yaml 3.1.3 [collection source_span string_scanner]

Additional context and comments

No response

[SelaseKay]

Hi @MERCURY-76, I'm unable able to reproduce this issue for your steps. Could you provide a complete reproducible example in the form of repository I can clone to investigate further? I tried reproducing with the example below:

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp(options: DefaultFirebaseOptions.currentPlatform);
  await initializeFirestore();

  runApp(const MyApp());
}

Future<void> initializeFirestore() async {
  try {
    final app = Firebase.app();
    
    // Create first Firestore instance with custom database
    final mainFirestore = FirebaseFirestore.instanceFor(
      app: app,
      databaseId: 'main-db',
    );
    
    mainFirestore.settings = const Settings(
      persistenceEnabled: true,
      cacheSizeBytes: Settings.CACHE_SIZE_UNLIMITED,
    );
    
    // Create second Firestore instance with another custom database
    final appConfig = FirebaseFirestore.instanceFor(
      app: app,
      databaseId: 'app-config',
    );
    
    appConfig.settings = const Settings(
      persistenceEnabled: true,
      cacheSizeBytes: Settings.CACHE_SIZE_UNLIMITED,
    );
    
    print('[FirestoreService] Initialization completed successfully');
    print('[FirestoreService] Main DB: ${mainFirestore.databaseId}');
    print('[FirestoreService] Config DB: ${appConfig.databaseId}');
  } catch (e) {
    print('[FirestoreService] Error during initialization: $e');
    rethrow;
  }
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Firestore Multi-Instance Bug',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        useMaterial3: true,
      ),
      home: const HomePage(),
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Firestore Multi-Instance Test'),
        backgroundColor: Colors.blue,
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            const Icon(
              Icons.check_circle,
              color: Colors.green,
              size: 64,
            ),
            const SizedBox(height: 24),
            const Text(
              'App Initialized Successfully',
              style: TextStyle(
                fontSize: 20,
                fontWeight: FontWeight.bold,
              ),
            ),
            const SizedBox(height: 16),
            const Padding(
              padding: EdgeInsets.symmetric(horizontal: 32),
              child: Text(
                'Two Firestore instances have been initialized.',
                textAlign: TextAlign.center,
                style: TextStyle(fontSize: 16),
              ),
            ),
            const SizedBox(height: 32),
            Container(
              padding: const EdgeInsets.all(16),
              margin: const EdgeInsets.symmetric(horizontal: 32),
              decoration: BoxDecoration(
                color: Colors.orange.shade50,
                border: Border.all(color: Colors.orange),
                borderRadius: BorderRadius.circular(8),
              ),
              child: const Column(
                children: [
                  Icon(Icons.warning_amber, color: Colors.orange, size: 32),
                  SizedBox(height: 8),
                  Text(
                    'To reproduce the bug:',
                    style: TextStyle(
                      fontWeight: FontWeight.bold,
                      fontSize: 16,
                    ),
                  ),
                  SizedBox(height: 8),
                ],
              ),
            ),
          ],
        ),
      ),
    );
  }

[MERCURY-76]

Hi @SelaseKay, my setup — it includes multiple Firestore instances with custom database IDs, hybrid local caching (Isar + Firestore), and separate flavors (dev and prod) for both iOS and Android.
I suspect the flavor configuration might be causing some conflicts during Firebase initialization, which could be related to the issue I’m seeing.
I’d like to share some of these environment-specific details privately, since they might not be relevant to everyone here.
Do you have an email or any preferred contact method?