How do I fix 'namespace not specified' error in Android Studio?

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.

I am getting this error after upgrading to Android Studio Flamingo and after giving AGP Upgrade Assistant from 7.4.2 to 8.0.0.

This is for an ionic project so the namespace is already specified in the build.gradle file like so,

build.gradle

apply plugin: 'com.android.application'

android {

    namespace 'com.example.m'
    compileSdkVersion rootProject.ext.compileSdkVersion
    defaultConfig {
        applicationId "io.ionic.starter"
        minSdkVersion rootProject.ext.minSdkVersion
        targetSdkVersion rootProject.ext.targetSdkVersion
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
        aaptOptions {
             // Files and dirs to omit from the packaged assets dir, modified to accommodate modern web apps.
             // Default: https://android.googlesource.com/platform/frameworks/base/+/282e181b58cf72b6ca770dc7ca5f91f135444502/tools/aapt/AaptAssets.cpp#61
            ignoreAssetsPattern '!.svn:!.git:!.ds_store:!*.scc:.*:!CVS:!thumbs.db:!picasa.ini:!*~'
        }
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

repositories {
    flatDir{
        dirs '../capacitor-cordova-android-plugins/src/main/libs', 'libs'
    }
}

dependencies {
    implementation fileTree(include: ['*.jar'], dir: 'libs')
    implementation "androidx.appcompat:appcompat:$androidxAppCompatVersion"
    implementation "androidx.coordinatorlayout:coordinatorlayout:$androidxCoordinatorLayoutVersion"
    implementation "androidx.core:core-splashscreen:$coreSplashScreenVersion"
    implementation project(':capacitor-android')
    testImplementation "junit:junit:$junitVersion"
    androidTestImplementation "androidx.test.ext:junit:$androidxJunitVersion"
    androidTestImplementation "androidx.test.espresso:espresso-core:$androidxEspressoCoreVersion"
    implementation project(':capacitor-cordova-android-plugins')
}

apply from: 'capacitor.build.gradle'

try {
    def servicesJSON = file('google-services.json')
    if (servicesJSON.text) {
        apply plugin: 'com.google.gms.google-services'
    }
} catch(Exception e) {
    logger.info("google-services.json not found, google-services plugin not applied. Push Notifications won't work")
}

I tried adding the namespace to AndroidManifest.xml as a package name and as a namespace attribute in the build.gradle also. Still getting the same error.

Solution

This error occurs after Android Gradle Plugin updated >= 8.x.x. To get rid of error use following method:

Open your flutter project's Android folder via Android Studio
Use AGP Upgrade Assistant to update gradle version. To do that, if your project's gradle version is 7.x.x just wait. When building gradle file finish, you will some popup in the bottom-right corner of screen.
Click start AGP Upgrade Assistant and process upgrading.
After upgrade process finished, update your top-level gradle file like following.:

buildscript {
    ext.kotlin_version = '1.8.22'
    repositories {
        google()
        mavenCentral()
    }

    dependencies {
        classpath 'com.android.tools.build:gradle:8.1.2'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
    }
}

allprojects {
    repositories {
        google()
        mavenCentral()
    }
    // This code is where all the magic happens and fixes the error.
    subprojects {
        afterEvaluate { project ->
            if (project.hasProperty('android')) {
                project.android {
                    if (namespace == null) {
                        namespace project.group
                    }
                }
            }
        }
    }
    // This code is where all the magic happens and fixes the error.
}

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

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

Rebuild and it should be working. If it is not working go File > Invalidate Caches and restart Android studio. After these process, you should be able to run your flutter android app without problem!

What was the problem?

Problem is about namespace. Earlier versions of gradle, they removed namespace from AndroidManifest.xml and transfer to gradle file. Even your project's namespace is transferred to new system, some flutter plugins may not be updated to recent gradle versions.

SOLUTION

To fix that, we are adding following code into top-level gradle file for adding namespace its sub-projects (plugins) via gradle.

  subprojects {
    afterEvaluate { project ->
        if (project.hasProperty('android')) {
            project.android {
                if (namespace == null) {
                    namespace project.group
                }
            }
        }
    }
}

For gradle.kts

allprojects {
    repositories {
        google()
        mavenCentral()
    }
    subprojects {
        afterEvaluate {
            if (plugins.hasPlugin("com.android.application") || plugins.hasPlugin("com.android.library")) {
                extensions.findByType(BaseExtension::class.java)?.let { androidExt ->
                    if (androidExt.namespace == null) {
                        androidExt.namespace = name
                    }
                }
            }
        }
    }
}