Flutter Firestore causing D8: Cannot fit requested classes in a single dex file (# methods: 71610 > 65536) in Android Studio

I am attempting to use firestore with a Flutter app in latest version of Android Studio. I have followed these instructions exactly. https://www.youtube.com/watch?v=DqJ_KjFzL9I&list=PLjxrf2q8roU2HdJQDjJzOeO6J3FoFLWr2&index=9 I even got them to work last week with a different app. Now I get the following error when I attempt to run my new app after completing all the steps up to (and including) updating pubspec.yaml. Keep in mind, in this example, i am getting the error on a fresh flutter counter app with no other code changes but what you see here.

D8: Cannot fit requested classes in a single dex file (# methods: 71610 > 65536)

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:transformDexArchiveWithExternalLibsDexMergerForDebug'.
> com.android.builder.dexing.DexArchiveMergerException: Error while merging dex archives: C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\2.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\3.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\4.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\5.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\6.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\7.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\8.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\9.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\10.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\11.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\12.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\13.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\14.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\15.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\16.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\17.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\18.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\19.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\20.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\21.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\22.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\23.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\24.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\25.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\26.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\27.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\28.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\29.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\30.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\31.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\32.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\33.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\34.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\35.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\36.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\37.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\38.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\39.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\40.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\41.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\42.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\43.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\44.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\45.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\46.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\47.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\48.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\49.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\50.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\51.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\52.jar, C:\Users\DonBo\AndroidStudioProjects\don_flutter_projects\bakery\bakery\build\app\intermediates\transforms\dexBuilder\debug\53.jar
  The number of method references in a .dex file cannot exceed 64K.
  Learn how to resolve this issue at https://developer.android.com/tools/building/multidex.html

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 21s
Finished with error: Gradle task assembleDebug failed with exit code 1

Here is my pubspec file

name: bakery
description: A new Flutter application.

# 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: ">=2.1.0 <3.0.0"

dependencies:

  cloud_firestore:

  flutter:
    sdk: flutter

  # The following adds the Cupertino Icons font to your application.
  # Use with the CupertinoIcons class for iOS style icons.
  cupertino_icons: ^0.1.2

dev_dependencies:
  flutter_test:
    sdk: flutter


# For information on the generic Dart part of this file, see the
# following page: https://www.dartlang.org/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

  # 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.io/assets-and-images/#resolution-aware.

  # For details regarding adding assets from package dependencies, see
  # https://flutter.io/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.io/custom-fonts/#from-packages

Here is my app level gradle file

def localProperties = new Properties()
def localPropertiesFile = rootProject.file('local.properties')
if (localPropertiesFile.exists()) {
    localPropertiesFile.withReader('UTF-8') { reader ->
        localProperties.load(reader)
    }
}

def flutterRoot = localProperties.getProperty('flutter.sdk')
if (flutterRoot == null) {
    throw new GradleException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
}

def flutterVersionCode = localProperties.getProperty('flutter.versionCode')
if (flutterVersionCode == null) {
    flutterVersionCode = '1'
}

def flutterVersionName = localProperties.getProperty('flutter.versionName')
if (flutterVersionName == null) {
    flutterVersionName = '1.0'
}

apply plugin: 'com.android.application'
apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"

android {
    compileSdkVersion 28

    lintOptions {
        disable 'InvalidPackage'
    }

    defaultConfig {
        // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
        applicationId "com.boody.sag.bakery"
        minSdkVersion 16
        targetSdkVersion 28
        versionCode flutterVersionCode.toInteger()
        versionName flutterVersionName
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            // TODO: Add your own signing config for the release build.
            // Signing with the debug keys for now, so `flutter run --release` works.
            signingConfig signingConfigs.debug
        }
    }
}

flutter {
    source '../..'
}

dependencies {
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
}

apply plugin: 'com.google.gms.google-services'

Here is my android level gradle file

buildscript {
    repositories {
        google()
        jcenter()
    }

    dependencies {
        classpath 'com.android.tools.build:gradle:3.2.1'
        classpath 'com.google.gms:google-services:3.2.0'
    }
}

allprojects {
    repositories {
        google()
        jcenter()
    }
}

rootProject.buildDir = '../build'
subprojects {
    project.buildDir = "${rootProject.buildDir}/${project.name}"
}
subprojects {
    project.evaluationDependsOn(':app')
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

Enable multidex.

Open project/app/build.gradle and add the following lines.

defaultConfig {
    ...

    multiDexEnabled true
}

and

dependencies {
    ...

    implementation 'com.android.support:multidex:1.0.3'
}

If you have migrated to AndroidX, you'll want this instead (tip by Touré Holder):

dependencies {
    ...

    implementation 'androidx.multidex:multidex:2.0.1'
}

By default, Flutter supports Android SDK v16 (Jelly Bean, released 2012), but multidex doesn't really work with Jelly Bean out of the box. There are two ways to fix this:

A) Change minimum target SDK

1. Open android/app/build.gradle, then find the line that says minSdkVersion 16.
2. Change that line to minSdkVersion 21.
3. Save the file.

B) Enable multidex.

If you want to support older Android versions you can use the multidex support library.

1. Open and modify project/app/build.gradle file to enable multidex and add the multidex library as a dependency, as shown here :

android {
    defaultConfig {
        ...
        multiDexEnabled true
    }
    ...
}

dependencies {
  implementation 'com.android.support:multidex:1.0.3'
}

Official guide here

Add this to android/app/build.gradle:

defaultConfig {
    ...
    multiDexEnabled true
}

I had the same error, so what I did was I increased the minSdkVersion of app-level Gradle file from 16 to 21. Now it works fine.

In the folder

> android/app/build.gradle

change the minSdkVersion to 21

android {
    defaultConfig {
        ...
        minSdkVersion 21
        targetSdkVersion 28
        multiDexEnabled true
    }
    ...
}

Ref: https://developer.android.com/studio/build/multidex

Another solution is just changing debug min sdk 21 for debug mode, leaving 16 for release. Build time will not be increased and everything will be working just fine.

// open android/app/build.gradle

buildTypes { 
    ... 
    // add this line
    debug { defaultConfig.minSdkVersion 21 }
}

Set multiDexEnabled true in builld.gradle defaultConfig

and also add implementation 'androidx.multidex:multidex:2.0.1' or
implementation 'com.android.support:multidex:1.0.3' to dependencies

Its easy just increase this minSdkVersion, targetSdkVersion :

Old:

defaultConfig {
        minSdkVersion 19
        targetSdkVersion 28
        versionCode flutterVersionCode.toInteger()
        versionName flutterVersionName
    }

New:

defaultConfig {
        minSdkVersion 21
        targetSdkVersion 29
        versionCode flutterVersionCode.toInteger()
        versionName flutterVersionName
    }

also this compileSdkVersion:

Old:

android {
    compileSdkVersion 28

New:

android {
    compileSdkVersion 29

I had this problem and in my case was related to dependencies of Firebase, Firestore etc, which I was not using anymore. I just delete it and that run ok.

A sugestion is to open a new project to take a copy of its gradle, make a isolation in the gradle of your project by / / and replace by a new one and make adjustments if necessary.