"Unable to load asset: null" in my flutter app

Question

When my app loads, no image loads at all, and t just crashes and i keep getting this error in my flutter app but I can't seem to find the problem, usually, when it can't find load an asset it tells me which asset, but this time it just says unable to load asset null, I don't know how to find the problem

it shows a breakpoint at this point

/// An [AssetBundle] that loads resources using platform messages.
class PlatformAssetBundle extends CachingAssetBundle {
  @override
  Future<ByteData> load(String key) async {
    final Uint8List encoded = utf8.encoder.convert(Uri(path: Uri.encodeFull(key)).path);
    final ByteData? asset =
        await defaultBinaryMessenger.send('flutter/assets', encoded.buffer.asByteData());
    if (asset == null)
      throw FlutterError('Unable to load asset: $key');   ******RIGHT HERE IS THE BREAKPOINT
    return asset;
  }
}

this is pub yaml file

name: wepay
description: A new Flutter project.

# The following line prevents the package from being accidentally published to
# pub.dev using `pub publish`. This is preferred for private packages.
publish_to: 'none' # Remove this line if you wish to publish to pub.dev

# The following defines the version and build number for your application.
# A version number is three numbers separated by dots, like 1.2.43
# followed by an optional build number separated by a +.
# Both the version and the builder number may be overridden in flutter
# build by specifying --build-name and --build-number, respectively.
# In Android, build-name is used as versionName while build-number used as versionCode.
# Read more about Android versioning at https://developer.android.com/studio/publish/versioning
# In iOS, build-name is used as CFBundleShortVersionString while build-number used as CFBundleVersion.
# Read more about iOS versioning at
# https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
version: 1.0.0+1

environment:
  sdk: ">=2.7.0 <3.0.0"

dependencies: 
  flutter:
    sdk: flutter
    


  # The following adds the Cupertino Icons font to your application.
  # Use with the CupertinoIcons class for iOS style icons.
  cupertino_icons: ^1.0.0

dev_dependencies: 
  flutter_test:
    sdk: flutter
  
  flutter_launcher_icons: "^0.8.0"
  page_indicator: ^0.3.0
  twitter_qr_scanner: any
  audioplayers: ^0.16.2
  modal_bottom_sheet: 0.2.2 
  overlay_screen: ^1.2.0+1 
  show_up_animation: ^1.0.4
  flutter_spinkit: "^4.1.2"
  auto_size_text: ^2.1.0
  cloud_firestore: ^0.14.0 
  firebase_core : ^0.5.0
  qr_flutter: ^3.2.0
  intl: ^0.16.1
  secure_random: ^1.0.0 
  fluttertoast: ^7.0.1
  clipboard: ^0.1.2+8
  social_share: ^2.0.5


 










    
flutter_icons:
  android: "icon"
  ios: true
  image_path: "assets/images/icon.png"


 

  
  

# For information on the generic Dart part of this file, see the
# following page: https://dart.dev/tools/pub/pubspec

# The following section is specific to Flutter.
flutter:

  # The following line ensures that the Material Icons font is
  # included with your application, so that you can use the icons in
  # the material Icons class.
  uses-material-design: true

  assets: 
   
    - assets/images/
    - assets/sounds/scan.mp3
    
    

  # To add assets to your application, add an assets section, like this:
  # assets:
  #   - images/a_dot_burr.jpeg
  #   - images/a_dot_ham.jpeg

  # An image asset can refer to one or more resolution-specific "variants", see
  # https://flutter.dev/assets-and-images/#resolution-aware.

  # For details regarding adding assets from package dependencies, see
  # https://flutter.dev/assets-and-images/#from-packages

  # To add custom fonts to your application, add a fonts section here,
  # in this "flutter" section. Each entry in this list should have a
  # "family" key with the font family name, and a "fonts" key with a
  # list giving the asset and other descriptors for the font. For
  # example:
  
  fonts:
    - family: Montserrat
      fonts:
        - asset: assets/fonts/Montserrat-Black.ttf
          weight: 900
        - asset: assets/fonts/Montserrat-Bold.ttf
          weight: 700
        - asset: assets/fonts/Montserrat-ExtraBold.ttf
          weight: 800
        - asset: assets/fonts/Montserrat-Medium.ttf
          weight: 500
        - asset: assets/fonts/Montserrat-Regular.ttf
          weight: 400
        - asset: assets/fonts/Montserrat-SemiBold.ttf
          weight: 600
    - family: Roboto
      fonts:
        - asset: assets/fonts/Roboto-Regular.ttf
        - asset: assets/fonts/Roboto-Bold.ttf
        - asset: assets/fonts/Roboto-Light.ttf
    



 

  # To add assets to your application, add an assets section, like this:
  # assets:
  #   - images/a_dot_burr.jpeg
  #   - images/a_dot_ham.jpeg

  # An image asset can refer to one or more resolution-specific "variants", see
  # https://flutter.dev/assets-and-images/#resolution-aware.

  # For details regarding adding assets from package dependencies, see
  # https://flutter.dev/assets-and-images/#from-packages

  # To add custom fonts to your application, add a fonts section here,
  # in this "flutter" section. Each entry in this list should have a
  # "family" key with the font family name, and a "fonts" key with a
  # list giving the asset and other descriptors for the font. For
  # example:
  # fonts:
  #   - family: Schyler
  #     fonts:
  #       - asset: fonts/Schyler-Regular.ttf
  #       - asset: fonts/Schyler-Italic.ttf
  #         style: italic
  #   - family: Trajan Pro
  #     fonts:
  #       - asset: fonts/TrajanPro.ttf
  #       - asset: fonts/TrajanPro_Bold.ttf
  #         weight: 700
  #
  # For details regarding fonts from package dependencies,
  # see https://flutter.dev/custom-fonts/#from-packages

Answer 1

This is the most common error.

It's because of spacing mistake you have in "assets:" in the pubspec.yaml

You should change the indentation spacing for assets

flutter:

  assets:
    - images/apple.png
    - images/apple1.png

Maintain this correct spacing:

flutter:

[2 whitespaces or 1 tab]assets:
[3 whitespaces]- images/pizza1.png
[3 whitespaces]- images/pizza0.png

Answer 2

In your pubspec.yaml you need to specify every single folder you want to use. Just the folder name is enough if you want to include all the files inside. Like this:

flutter:
  uses-material-design: true

  assets: 
    - assets/
    - assets/images/
    - assets/sounds/

Make sure the two spaces indentation in YAML files.

And try to replace

await defaultBinaryMessenger.send('flutter/assets', encoded.buffer.asByteData());

with

await ServicesBinding.instance.defaultBinaryMessenger.send('flutter/assets', encoded.buffer.asByteData());

Don't forget to add:

import 'binding.dart';

Try if this works for you.