Error while Dexing when building Flutter project

Question

I am currently trying to integrate Firebase Messaging into my project, I have set up a firebase project and successfully imported all of the other dependencies I need (crashlytics, firestore etc...) however when I add the firebase messaging dependency to my pubspec.yaml I get an error when building. I am using the newest version of firebase_messaging and also the newest version of google services.

The Error:

Plugin project: firebase_core_web not found. Please update settings.gradle.
Invalid depfile: C:\Users\Owner\AndroidStudioProjects\switcheroo_ios\.dart_tool\flutter_build\d71b8b11f916190e0bd095c78ccf0a69\kernel_snapshot.d
Invalid depfile: C:\Users\Owner\AndroidStudioProjects\switcheroo_ios\.dart_tool\flutter_build\d71b8b11f916190e0bd095c78ccf0a69\kernel_snapshot.d
AGPBI: {"kind":"error","text":"Type com.google.firebase.iid.zzbb is referenced as an interface from `com.google.firebase.messaging.zzf`.","sources":[{}],"tool":"D8"}

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:mergeExtDexDebug'.
> Could not resolve all files for configuration ':app:debugRuntimeClasspath'.
   > Failed to transform artifact 'firebase-messaging.aar (com.google.firebase:firebase-messaging:20.0.1)' to match attributes {artifactType=android-dex, dexing-enable-desugaring=true, dexing-is-debuggable=true, dexing-min-sdk=21}.
      > Execution failed for DexingWithClasspathTransform: C:\Users\Owner\.gradle\caches\transforms-2\files-2.1\ac2c922e894bed89371853ed7d90bb4e\jetified-firebase-messaging-20.0.1\jars\classes.jar.
         > Error while dexing.

App Gradle:

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 plugin: 'kotlin-android'
apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"
apply plugin: 'com.google.gms.google-services'
apply plugin: 'com.google.firebase.crashlytics'

android {
    compileSdkVersion 28

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

    lintOptions {
        disable 'InvalidPackage'
    }

    defaultConfig {
        // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
        applicationId "com.barbecu.switcherooIOS"
        minSdkVersion 21
        targetSdkVersion 28
        versionCode flutterVersionCode.toInteger()
        versionName flutterVersionName
    }

    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 {
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    implementation 'com.google.firebase:firebase-crashlytics:17.0.1'
}

Project Gradle:

buildscript {
    ext.kotlin_version = '1.3.50'
    repositories {
        google()
        jcenter()
    }

    dependencies {
        classpath 'com.android.tools.build:gradle:3.5.0'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
        classpath 'com.google.gms:google-services:4.3.3'
        classpath 'com.google.firebase:firebase-crashlytics-gradle:2.1.1'
    }
}

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
}

Answer 1

Try adding

implementation 'com.google.firebase:firebase-messaging:20.0.1'

inside dependencies

just try adding dependencies that r related to each platform explicitly like in android as above

for ios (im not sure about ios ecosystem) but adding this might help

pod 'Firebase/Messaging'