Flutter Android show "System down for maintenance: We're sorry, our system is not available"

Question

I'm new to Flutter. I have built this app running on Android. When I try to run on a mobile device, the mobile device shows an error message:

System down for maintenance: We're sorry, our system is not available.

I don't know what is wrong. I've searched the solution and didn't find the answer. So I asking here hope get some help.

Here, I attach the logcat:

W/FlutterActivityAndFragmentDelegate(31352): A splash screen was provided to Flutter, but this is deprecated. See flutter.dev/go/android-splash-migration for migration steps.
Debug service listening on ws://127.0.0.1:63724/P7glDWK-zhc=/ws
Syncing files to device Nexus 5...
I/DynamiteModule(31352): Considering local module com.google.android.gms.ads.dynamite:0 and remote module com.google.android.gms.ads.dynamite:214106404
I/DynamiteModule(31352): Selected remote version of com.google.android.gms.ads.dynamite, version >= 214106404
D/DynamitePackage(31352): Instantiated singleton DynamitePackage.
D/DynamitePackage(31352): Instantiating com.google.android.gms.ads.ChimeraMobileAdsSettingManagerCreatorImpl
I/Ads     (31352): Updating ad debug logging enablement.
W/ConnectionStatusConfig(31352): Dynamic lookup for intent failed for action: com.google.android.gms.leibniz.events.service.START
W/GmsClient(31352): unable to connect to service: com.google.android.gms.leibniz.events.service.START on com.google.android.gms
I/art     (31352): Rejecting re-init on previously-failed class java.lang.Class<PE0>
I/art     (31352): Rejecting re-init on previously-failed class java.lang.Class<PE0>
E/libEGL  (31352): validate_display:255 error 3008 (EGL_BAD_DISPLAY)
W/cr_media(31352): Requires BLUETOOTH permission
W/Ads     (31352): Update ad debug logging enablement as false
E/libEGL  (31352): validate_display:255 error 3008 (EGL_BAD_DISPLAY)
V/OneSignal(31352): Initializing the OneSignal Flutter SDK (2.2.0)
D/OneSignal(31352): OneSignal SessionManager initSessionFromCache
D/OneSignal(31352): OneSignal InAppMessageTracker initInfluencedTypeFromCache: OSChannelTracker{tag=iam_id, influenceType=UNATTRIBUTED, indirectIds=null, directId='null'}
D/OneSignal(31352): OneSignal NotificationTracker initInfluencedTypeFromCache: OSChannelTracker{tag=notification_id, influenceType=UNATTRIBUTED, indirectIds=null, directId='null'}
D/OneSignal(31352): OneSignal getUnattributedUniqueOutcomeEventsSentByChannel: []
E/OneSignal(31352): Cannot change requiresUserPrivacyConsent() from TRUE to FALSE
D/OneSignal(31352): redisplayedInAppMessages: []
D/OneSignal(31352): Attempted to clean 6 month old IAM data, but none exists!
I/OneSignal(31352): Restoring notifications
D/OneSignal(31352): Starting new session
D/OneSignal(31352): OneSignal cleanOutcomes for session
D/OneSignal(31352): OneSignal save unattributedUniqueOutcomeEvents: []
D/OneSignal(31352): OneSignal SessionManager restartSessionIfNeeded with entryAction: APP_CLOSE
D/OneSignal(31352):  channelTrackers: []
D/OneSignal(31352): OneSignal SessionManager sendSessionEndingWithInfluences with influences: []
D/OneSignal(31352): initWithCachedInAppMessages: null
I/OneSignal(31352): Querying DB for notifs to restore: created_time > 1642402574 AND dismissed = 0 AND opened = 0 AND is_summary = 0 AND expire_time > 1643007374
D/OneSignal(31352): LocationController sendAndClearPromptHandlers from non prompt flow
D/OneSignal(31352): registerUser:registerForPushFired:false, locationFired: true, remoteParams: null, appId: eeb5fc7d-0c5a-4f80-8ac8-cb6e029f4c1f
D/OneSignal(31352): Starting request to get Android parameters.
D/OneSignal(31352): OneSignalRestClient: Making request to: https://api.onesignal.com/apps/eeb5fc7d-0c5a-4f80-8ac8-cb6e029f4c1f/android_params.js?player_id=742aac25-d8c6-40b1-907f-3dcde944d927
D/OneSignal(31352): OneSignalRestClient: Adding header if-none-match: W/"699d1d1289a72c686eb3cbb40b190085"
V/OneSignal(31352): OneSignalRestClient: After con.getResponseCode to: https://api.onesignal.com/apps/eeb5fc7d-0c5a-4f80-8ac8-cb6e029f4c1f/android_params.js?player_id=742aac25-d8c6-40b1-907f-3dcde944d927
D/OneSignal(31352): OneSignalRestClient: GET - Using Cached response due to 304: {"awl_list":{},"android_sender_id":"597897739377","chnl_lst":[],"outcomes":{"direct":{"enabled":false},"indirect":{"notification_attribution":{"minutes_since_displayed":60,"limit":10},"enabled":false},"unattributed":{"enabled":false}},"receive_receipts_enable":false}
D/OneSignal(31352): OneSignal saveInfluenceParams: InfluenceParams{indirectNotificationAttributionWindow=60, notificationLimit=10, indirectIAMAttributionWindow=1440, iamLimit=10, directEnabled=false, indirectEnabled=false, unattributedEnabled=false}
W/ComponentDiscovery(31352): Class com.google.firebase.dynamicloading.DynamicLoadingRegistrar is not an found.
I/FirebaseApp(31352): Device unlocked: initializing all Firebase APIs for app ONESIGNAL_SDK_FCM_APP_NAME
I/OneSignal(31352): Device registered, push token = eSwBJFILTvWNtzszLTE097:APA91bF-W2DUnRY58ROKO30YOhhch0GrkVG7YEQLs1A66-uEH19JF-R5sEByh8xb0_npzaEkixjKhnldX3LrEsnHzJKTwg3F6WygUHvtGZkp2xMYeW6FOO7acYjDbGJIzE1E5ZNdRTRL
D/OneSignal(31352): registerUser:registerForPushFired:true, locationFired: true, remoteParams: com.onesignal.OneSignalRemoteParams$2@cc8e9d4, appId: eeb5fc7d-0c5a-4f80-8ac8-cb6e029f4c1f
I/flutter (31352): value read from storage: null
D/OneSignal(31352): OneSignalRestClient: Making request to: https://api.onesignal.com/players/742aac25-d8c6-40b1-907f-3dcde944d927/on_session
D/OneSignal(31352): OneSignalRestClient: POST SEND JSON: {"app_id":"eeb5fc7d-0c5a-4f80-8ac8-cb6e029f4c1f"}
V/OneSignal(31352): OneSignalRestClient: After con.getResponseCode to: https://api.onesignal.com/players/742aac25-d8c6-40b1-907f-3dcde944d927/on_session
D/OneSignal(31352): OneSignalRestClient: Successfully finished request to: https://api.onesignal.com/players/742aac25-d8c6-40b1-907f-3dcde944d927/on_session
D/OneSignal(31352): OneSignalRestClient: POST RECEIVED JSON: {"success":true,"id":"742aac25-d8c6-40b1-907f-3dcde944d927"}
D/OneSignal(31352): doCreateOrNewSession:response: {"success":true,"id":"742aac25-d8c6-40b1-907f-3dcde944d927"}
I/OneSignal(31352): Device registered, UserId = 742aac25-d8c6-40b1-907f-3dcde944d927
D/OneSignal(31352): onActivityPaused: com.polarlabsen.MainActivity@de49c40
D/OneSignal(31352): curActivity is NOW: null
D/OneSignal(31352): onActivityStopped: com.polarlabsen.MainActivity@de49c40
D/OneSignal(31352): curActivity is NOW: null
D/OneSignal(31352): Application lost focus
D/OneSignal(31352): GMSLocationController onFocusChange!
D/OneSignal(31352): FocusTimeProcessorUnattributed:timeTypeApplies for influences: [SessionInfluence{influenceChannel=notification, influenceType=DISABLED, ids=null}] true
D/OneSignal(31352): FocusTimeProcessorUnattributed:addTime with lastFocusTimeInfluences: [SessionInfluence{influenceChannel=notification, influenceType=DISABLED, ids=null}]
D/OneSignal(31352): FocusTimeProcessorUnattributed:getUnsentActiveTime: 41
D/OneSignal(31352): FocusTimeProcessorUnattributed:saveUnsentActiveTime: 62
D/OneSignal(31352): FocusTimeProcessorUnattributed:getUnsentActiveTime: 62
V/OneSignal(31352): scheduleSyncTask:SYNC_AFTER_BG_DELAY_MS: 30000
V/OneSignal(31352): scheduleSyncServiceAsJob:atTime: 30000
I/OneSignal(31352): scheduleSyncServiceAsJob:result: 1
D/OneSignal(31352): FocusTimeProcessorUnattributed:getUnsentActiveTime: 62
D/OneSignal(31352): FocusTimeProcessorUnattributed:getUnsentActiveTime: 62
D/OneSignal(31352): FocusTimeProcessorUnattributed:sendOnFocus with totalTimeActive: 62
D/OneSignal(31352): OneSignalRestClient: Making request to: https://api.onesignal.com/players/742aac25-d8c6-40b1-907f-3dcde944d927/on_focus
D/OneSignal(31352): OneSignalRestClient: POST SEND JSON: {"app_id":"eeb5fc7d-0c5a-4f80-8ac8-cb6e029f4c1f","type":1,"state":"ping","active_time":62,"device_type":1,"net_type":0}
V/OneSignal(31352): OneSignalRestClient: After con.getResponseCode to: https://api.onesignal.com/players/742aac25-d8c6-40b1-907f-3dcde944d927/on_focus
D/OneSignal(31352): OneSignalRestClient: Successfully finished request to: https://api.onesignal.com/players/742aac25-d8c6-40b1-907f-3dcde944d927/on_focus
D/OneSignal(31352): OneSignalRestClient: POST RECEIVED JSON: {"id":"742aac25-d8c6-40b1-907f-3dcde944d927","success":true}
D/OneSignal(31352): FocusTimeProcessorUnattributed:saveUnsentActiveTime: 0