Android getting error: Namespace not specified

I decided to use latest version of Gradle and after updating AndroidManifest.xml and build.gradle I get this error and I couldn't solve it

Error:

Namespace not specified. Please specify a namespace in the module's build.gradle file like so:

android {
    namespace 'com.example.namespace'
}

If the package attribute is specified in the source AndroidManifest.xml, it can be migrated automatically to the namespace value in the build.gradle file using the AGP Upgrade Assistant; please refer to https://developer.android.com/studio/build/agp-upgrade-assistant for more information.

application build.gradle

dependencies {
    classpath 'com.android.tools.build:gradle:8.0.1'
    classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
}

gradle.wrapper.properties:

distributionUrl=https\://services.gradle.org/distributions/gradle-8.0-bin.zip

AndroidManifest.xml

<manifest xmlns:android="http://schemas.android.com/apk/res/android">
    <application
        android:label="xxxxx"
        android:name="${applicationName}"
        android:icon="@mipmap/ic_launcher">
        <activity
            android:name=".MainActivity"
            android:exported="true"
            android:launchMode="singleTop"
            android:theme="@style/LaunchTheme"
            android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
            android:hardwareAccelerated="true"
            android:windowSoftInputMode="adjustResize">
            
            <meta-data
              android:name="io.flutter.embedding.android.NormalTheme"
              android:resource="@style/NormalTheme"
              />
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
        
        <meta-data
            android:name="flutterEmbedding"
            android:value="2" />
    </application>
</manifest>

and build.gradle

plugins {
    id "com.android.application"
    id "kotlin-android"
    id "dev.flutter.flutter-gradle-plugin"
}

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.example.xxxxx"
    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 {
        applicationId "com.example.xxxxx"
        minSdkVersion flutter.minSdkVersion
        targetSdkVersion flutter.targetSdkVersion
        versionCode flutterVersionCode.toInteger()
        versionName flutterVersionName
    }

    buildTypes {
        release {
            signingConfig signingConfigs.debug
        }
    }
}

flutter {
    source '../..'
}

dependencies {}

I believe the namespace issue occurs because Gradle 8.x is currently supported by Java JDK 17, and not by versions 18 through 20.

The Gradle user guide hints at the incompatibilities:
https://docs.gradle.org/current/userguide/compatibility.html#java

I'm currently on Java 20, and motifying the AndroidManifest.xml and build.gradle with the namespace did not fix the issue for me either, but by downgrading to Gradle 7.4.2, I was able to get Flutter and Android Studio to build.

So my advice is to downgrade your version of Gradle, or downgrade your version of Java.

I have added the following lines to app/build.gradle

android{
    namespace 'com.example.application
    ....
}

be sure to add it to the build.gradle file found in the app folder no in the project folder.

In my Flutter project, I got the same error after the studio upgrade to Giraffe.
Basically from Giraffe onwards gradle only looks at the build file
namespace property than the manifest package property.

So I have migrated my app-level build.gradle file and manifest. But it was showing some package was missing the namespace.

So I opened the android folder separately in the studio and tried the AGP upgrade and found out some plugin gradle files were missing the namespace, once I added the namespace property to all of their build files everything worked.

Instead of using a namespace within your build.gradle file, use the applicationId as shown below,

 defaultConfig {
        applicationId "com.myApp.example"
        minSdkVersion 16
        targetSdkVersion 30
        versionCode 33
        versionName "0.3.4"

If this doesn't work for you, please make a new project setup and attempt to build your app using the new project setup.

file >> new project >> project folder path