Android Studio – Error when using File writeAsBytes in flutter android 11 Is there any other way it could work?

I am currently using flutter to save a photo, but I am getting an error.

E/flutter (14379): [ERROR:flutter/lib/ui/ui_dart_state.cc(199)] Unhandled Exception: FileSystemException: Cannot open file, path = '/storage/emulated/0/Pictures/FolderName/2021-10-14T22:02:34.9847821.jpg' (OS Error: Operation not permitted, errno = 1)
E/flutter (14379): #0      _File.open.<anonymous closure> (dart:io/file_impl.dart:356:9)
E/flutter (14379): #1      _rootRunUnary (dart:async/zone.dart:1362:47)
E/flutter (14379): #2      _CustomZone.runUnary (dart:async/zone.dart:1265:19)
E/flutter (14379): <asynchronous suspension>
E/flutter (14379): #3      AddGenuineDetailController.saveFileAndroid (package:projectName/controllers/my/addGenuineDetail_controller.dart:55:7)
E/flutter (14379): <asynchronous suspension>
E/flutter (14379): 

I want to save it to the path over there and use it. That’s because it appears in the Gallery app. However, in Android 11 or later, the file is not saved to that path. However, when saving to the internal storage where the app is installed, the file is saved.

The current build.gradle

android {
    compileSdkVersion 30

    sourceSets {
        main.java.srcDirs += 'src/main/kotlin'
    }

    defaultConfig {
        // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
        applicationId "com.company.projectName"
//        minSdkVersion 16
        minSdkVersion 20
        targetSdkVersion 29
        versionCode flutterVersionCode.toInteger()
        versionName flutterVersionName
        multiDexEnabled true
    }

Setting the target sdk to 28 had no effect.

AndroidManifest.xml Application

<application
        android:label="projectName"
        android:icon="@mipmap/ic_launcher"
        android:usesCleartextTraffic="true"
        android:requestLegacyExternalStorage="true"
        android:preserveLegacyExternalStorage="true"
        >

AndroidManifest.xml permission

    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
    <uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.ACCESS_MEDIA_LOCATION" />
    <uses-permission android:name="android.permission.CAMERA" />
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"/>
    <uses-permission android:name="android.permission.VIBRATE" />
    <uses-permission android:name="android.permission.WAKE_LOCK" />
    <uses-permission android:name="android.permission.USE_FULL_SCREEN_INTENT" />
    <uses-permission android:name="android.permission.REQUEST_COMPANION_USE_DATA_IN_BACKGROUND" />

Flutter code

  void saveFileAndroid() async {
    final savePath = "/storage/emulated/0/Pictures/ProjectName";
    final Directory directory = Directory("$savePath");
    print("저장소 유무 : ${await directory.exists()}");
    if(await directory.exists() != true){
      final Directory _appDocDirNewFolder = await directory.create(recursive: true);
      print("저장소 유무 : ${await directory.exists()}");
      print(_appDocDirNewFolder.path);
    }
    int i = 0;
    for(var file in certificateList){
      i += 1;
      var url = Uri.parse(GlobalApiService.getImage(file.path!));
      var res = await http.get(url);
      String imgName = "${model!.product.createdDate}$i.jpg";
      File saveImg = new File('${directory.path}/$imgName');
      await saveImg.writeAsBytes(Uint8List.fromList(res.bodyBytes));
    }
  }

Is there any way to save on Android 11 or higher?