Flutter release aab bundle so got NullPointerException error. (android App Bundle) - flutter

Question

FAILURE: Build failed with an exception.
What went wrong:
Execution failed for task ':app:signReleaseBundle'.
A failure occurred while executing com.android.build.gradle.internal.tasks.FinalizeBundleTask$BundleToolRunnable
java.lang.NullPointerException (no error message)
Try:
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Get more help at https://help.gradle.org
BUILD FAILED in 24s
Running Gradle task 'bundleRelease'... 26.2s
Gradle task bundleRelease failed with exit code 1
Build.gradle File:-
def localProperties = new Properties()
def localPropertiesFile = rootProject.file('local.properties')
if (localPropertiesFile.exists()) {
localPropertiesFile.withReader('UTF-8') { reader ->
localProperties.load(reader)
}
}
def flutterRoot = localProperties.getProperty('flutter.sdk')
if (flutterRoot == null) {
throw new GradleException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
}
def flutterVersionCode = localProperties.getProperty('flutter.versionCode')
if (flutterVersionCode == null) {
flutterVersionCode = '1'
}
def flutterVersionName = localProperties.getProperty('flutter.versionName')
if (flutterVersionName == null) {
flutterVersionName = '1.0'
}
apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"
def keystoreProperties = new Properties()
def keystorePropertiesFile = rootProject.file('key.properties')
if (keystorePropertiesFile.exists()) {
keystoreProperties.load(new FileInputStream(keystorePropertiesFile))
}
android {
compileSdkVersion 32
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 "co.demo.flutter"
minSdkVersion 21
multiDexEnabled true
targetSdkVersion 32
versionCode flutterVersionCode.toInteger()
versionName flutterVersionName
}
signingConfigs {
release {
keyAlias keystoreProperties['keyAlias']
keyPassword keystoreProperties['keyPassword']
storeFile keystoreProperties['storeFile'] ? file(keystoreProperties['storeFile']) : null
storePassword keystoreProperties['storePassword']
}
}
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.release
}
}
}
flutter {
source '../..'
}
dependencies {
implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
// implementation 'com.android.support:multidex:2.0.1'
implementation 'com.google.android.gms:play-services-tagmanager:17.0.0'
implementation "androidx.multidex:multidex:2.0.1"
}

Answer 1

I faced the same error.
In my case, the key.properties was missing.
I just added it in [project]/android/key.properties
The content of key.properties was;
storePassword=<password from previous step> (example: 12345678)
keyPassword=<password from previous step> (example: 12345678)
keyAlias=upload
storeFile=/Users/<user name>/upload-keystore.jks (Complete path of upload-keystore.jks
using "/" not "\")
After this I run this command to build the app bundle;
flutter build appbundle