Flutter应用启动报错：无法实例化MainActivity类

我是Flutter技术新手，正在跟随YouTube教程开发Flutter应用，此前运行正常但现在启动时出现报错。我使用的Flutter和Android版本比教程版本新，已经针对版本差异做了适配调整。以下是错误日志及相关Gradle配置文件：

错误日志 #

√  Built build\app\outputs\flutter-apk\app-debug.apk.
E/AndroidRuntime(30001): FATAL EXCEPTION: main
E/AndroidRuntime(30001): Process: com.themessagedoor.brew_crew, PID: 30001
E/AndroidRuntime(30001): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.themessagedoor.brew_crew/com.themessagedoor.brew_crew.MainActivity}: java.lang.ClassNotFoundException: Didn't find class "com.themessagedoor.brew_crew.MainActivity" on path: DexPathList[[zip file "/data/app/~~6HmKQ3PSpoVntRyC1E8eqw==/com.themessagedoor.brew_crew-KWS2PSLfkJPMtBcF_bjCKg==/base.apk"],nativeLibraryDirectories=[/data/app/~~6HmKQ3PSpoVntRyC1E8eqw==/com.themessagedoor.brew_crew-KWS2PSLfkJPMtBcF_bjCKg==/lib/x86_64, /data/app/~~6HmKQ3PSpoVntRyC1E8eqw==/com.themessagedoor.brew_crew-KWS2PSLfkJPMtBcF_bjCKg==/base.apk!/lib/x86_64, /system/lib64, /system_ext/lib64]]
E/AndroidRuntime(30001):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3551)
E/AndroidRuntime(30001):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3782)
E/AndroidRuntime(30001):    at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:101)
E/AndroidRuntime(30001):    at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
E/AndroidRuntime(30001):    at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
E/AndroidRuntime(30001):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2307)
E/AndroidRuntime(30001):    at android.os.Handler.dispatchMessage(Handler.java:106)
E/AndroidRuntime(30001):    at android.os.Looper.loopOnce(Looper.java:201)
E/AndroidRuntime(30001):    at android.os.Looper.loop(Looper.java:288)
E/AndroidRuntime(30001):    at android.app.ActivityThread.main(ActivityThread.java:7872)
E/AndroidRuntime(30001):    at java.lang.reflect.Method.invoke(Native Method)
E/AndroidRuntime(30001):    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548)
E/AndroidRuntime(30001):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:936)
E/AndroidRuntime(30001): Caused by: java.lang.ClassNotFoundException: Didn't find class "com.themessagedoor.brew_crew.MainActivity" on path: DexPathList[[zip file "/data/app/~~6HmKQ3PSpoVntRyC1E8eqw==/com.themessagedoor.brew_crew-KWS2PSLfkJPMtBcF_bjCKg==/base.apk"],nativeLibraryDirectories=[/data/app/~~6HmKQ3PSpoVntRyC1E8eqw==/com.themessagedoor.brew_crew-KWS2PSLfkJPMtBcF_bjCKg==/lib/x86_64, /data/app/~~6HmKQ3PSpoVntRyC1E8eqw==/com.themessagedoor.brew_crew-KWS2PSLfkJPMtBcF_bjCKg==/base.apk!/lib/x86_64, /system/lib64, /system_ext/lib64]]
E/AndroidRuntime(30001):    at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:259)
E/AndroidRuntime(30001):    at java.lang.ClassLoader.loadClass(ClassLoader.java:379)
E/AndroidRuntime(30001):    at java.lang.ClassLoader.loadClass(ClassLoader.java:312)
E/AndroidRuntime(30001):    at android.app.AppComponentFactory.instantiateActivity(AppComponentFactory.java:95)
E/AndroidRuntime(30001):    at androidx.core.app.CoreComponentFactory.instantiateActivity(CoreComponentFactory.java:45)
E/AndroidRuntime(30001):    at android.app.Instrumentation.newActivity(Instrumentation.java:1339)
E/AndroidRuntime(30001):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3538)
E/AndroidRuntime(30001):    ... 12 more
Application finished.

Android级别build.gradle #

buildscript {
    ext.kotlin_version = '1.7.10'
    repositories {
        google()
        mavenCentral()
    }

    dependencies {
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
        //check this if it's correct
        classpath "com.google.gms:google-services:4.4.0"
    }
}

  //  plugins {
    //    id("com.google.gms.google-services") version "4.0.1" apply false
    // }

allprojects {
    repositories {
        google()
        mavenCentral()
    }
}

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

tasks.register("clean", Delete) {
    delete rootProject.buildDir
}

应用级别build.gradle #

plugins {
    id "com.android.application"
    id "kotlin-android"
    id "dev.flutter.flutter-gradle-plugin"
    id("com.google.gms.google-services")
}

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

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

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

android {
    namespace "com.themessagedoor.brew_crew"
    compileSdkVersion flutter.compileSdkVersion
    ndkVersion flutter.ndkVersion

    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }

    kotlinOptions {
        jvmTarget = '1.8'
    }

    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.themessagedoor.brew_crew"
        // You can update the following values to match your application needs.
        // For more information, see: https://docs.flutter.dev/deployment/android#reviewing-the-gradle-build-configuration.
        minSdkVersion flutter.minSdkVersion
        targetSdkVersion flutter.targetSdkVersion
        versionCode flutterVersionCode.toInteger()
        versionName flutterVersionName
        multiDexEnabled true
    }

    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(platform("com.google.firebase:firebase-bom:32.7.0"))
}

我已经检查过代码和Gradle文件，仅存在为适配新版本Android及Flutter/Dart语言所做的差异。

内容的提问来源于stack exchange，提问作者hamtickell