Unhandled Exception: FileSystemException: Cannot open file, path ... (OS Error: No such file or directory, errno = 2)

I'm trying to download *.xlsx file using dio.download, and it's throwing the errors: Unhandled Exception: FileSystemException: Cannot open file, path = '/storage/emulated/0/Android/data/com.example.foodagator_app/files/file.xlsx' (OS Error: No such file or directory, errno = 2)

Another one error from try/catch block: FileSystemException: Creation failed, path = 'File: '' (OS Error: Read-only file system, errno = 30)

I wrote the permission in androidmanifest for external storage, and also tried temporary directory, but it's not working. Can anyone help me with this? Here is my code

void download() async {
    var tempDir = await getExternalStorageDirectory();
    File file = File(tempDir!.path + '/file.xlsx');
    try {
      Response response = await dio.download(
        url,
        file,
        options: Options(
          responseType: ResponseType.bytes,
          followRedirects: false,
        ),
      );

      var raf = file.openSync(mode: FileMode.write);
      // response.data is List<int> type
      raf.writeFromSync(response.data);
      await raf.close();
    } catch (e) {
      print('Error is: $e');
    }
  }

  void readFile() async {
    var tempDir = await getExternalStorageDirectory();

    var filePath = tempDir!.path + "/file.xlsx";
    var bytes = File(filePath).readAsBytesSync();
    var decoder = SpreadsheetDecoder.decodeBytes(bytes, update: true);
    for (var table in decoder.tables.keys) {
      print(table);
      print(decoder.tables[table]!.maxCols);
      print(decoder.tables[table]!.maxRows);
      for (var row in decoder.tables[table]!.rows) {
        print('$row');
      }
    }
  }