Error building Android library: Direct local .aar file dependencies are not supported

We recently upgraded to Android Gradle Plugin 4.0.0-beta03. We are now seeing this error when building one of our library modules

$ ./gradlew library_module:assemble

Execution failed for task ':library_module:bundleDebugAar'.
> Direct local .aar file dependencies are not supported when building an AAR.
The resulting AAR would be broken because the classes and Android resources from any local .aar
file dependencies would not be packaged in the resulting AAR. Previous versions of the Android
Gradle Plugin produce broken AARs in this case too (despite not throwing this error). The
following direct local .aar file dependencies of the :library_module project caused this error:
______.aar

I can see this was added to AGP a few months ago. But they provide no further info on why.

So.

1. What was the problem? Any more info? I can't find a single bug report anywhere.
2. How exactly can I fix this? Is this saying that I can't build one .aar that depends on other local .aars? What if this local aar was instead hosted on Maven Central or another remote repo? Why would that make a difference?

I recently encountered the same issue, the fix was to remove the library from libs/ and import it using File -> New -> New Module -> Import .JAR/.AAR Package, then referencing it in the library module build.gradle file:

dependencies {
  implementation project(":imported_aar_module")
}

If you are on a newer Android Studio version (4.0.0+), this option is not available. Instead you have to do it manually.

1. Create a new directory and put the following content into the build.gradle file withing the new directory:

configurations.maybeCreate("default")
artifacts.add("default", file('[nameOfTheAar].aar'))

2. Place the aar into this new directoy. Next to the build.gradle file.
3. Add the new created Gradle project to the settings.gradle file:

include(":pathToTheCreatedDirectory")

4. Include the project in your library where you want to use the aar:

implementation project(":pathToTheCreatedDirectory", configuration = "default")

When building an Android library that depends on other Android libraries (i.e., aar files), you will get the following error message if you include the aar files as dependencies in the project:

> Direct local .aar file dependencies are not supported when building an AAR. The resulting AAR would be broken because the classes and Android resources from any local .aar file dependencies would not be packaged in the resulting AAR. Previous versions of the Android Gradle Plugin produce broken AARs in this case too (despite not throwing this error).

As the above message states, when you build an Android library project, any aar it depends on is not packaged. If you built this way prior to AGP (Android Gradle Plugin) 4, you probably noticed that you had to include the aar dependencies on the project consuming your library.

You can compile your Android library project by specifying that the aar dependencies are compileOnly. See this for more info on when to use compileOnly.

So just add the following to your app build.gradle file:

compileOnly files('libs/some-library.aar')

Note that if you do this you will have to include the aar dependencies on the application project that consumes your library.

Alternatively, you can create a module that imports your aar dependency as @Sandi mentioned in the answer above.

Another way is to publish your aar dependencies to a maven repository and then add them to your library project like this:

implementation 'mylibrarygroup:mylibraryartifact:version-x.y.z@aar'

I want to call out @StefMa's comment on this question which was incredible simple and solved this issue for me, but it's buried among many other comments on this thread and is easily missed.

The 'correct' answer on this thread no longer works because it's not possible to import AARs in Android Studio anymore as referred to in that answer. But, the solution referred to in StefMa's comment linking to this GitHub post does, and it works perfectly.

Long story short - put your AAR into a separate module.

There's no need to muck around with creating lib directories, just follow these directions -

1. Create a new directory in your project's root directory. The image below shows two of them - spotify-app-remote and spotify-auth, but one is sufficient. Within that, put your AAR in, and create a new build.gradle file.

2. Within the build.gradle file, add the following, replacing the aar filename with the name of your AAR file -

configurations.maybeCreate("default")
artifacts.add("default", file('spotify-app-remote-release-0.7.1.aar'))

3. Add this to your settings.gradle file, substituting the name of the directory you created

include ':spotify-app-remote'

4. Include your new module in the module you wish to use the AAR. eg, if you want to use it within your app module, open app's build.gradle and add

api project(':spotify-app-remote')

within your dependencies { } block, obviously again substituting spotify-app-remote with whatever the name of your module is.

There are some changes now, You need to add your AAR or JAR as a dependency

1.) First, Navigate to File > Project Structure [Reference Image 1]

2.) Then go to Dependencies > Declared Dependencies tab, click and select JAR/AAR Dependency in the dropdown [Reference Image 2]

3.)In the Add Jar/Aar Dependency dialog, first enter the path to your .aar or .jar file, then select the configuration to which the dependency applies. If the library should be available to all configurations, select the "implementation" configuration. [Reference Image 3]

4.) Click OK then Apply > OK.

You are good to go.

In my experience, when Gradle Plugin version is 4.2.2+ and Gradle version is 7.1+, as in @Luis's answer 'compileOnly' works.

compileOnly files('libs/your_library_name.aar')

It didn't work when the Gradle versions were lower.

Getting same error when use this code.

implementation fileTree(include: ['*.jar'], dir: 'libs')
implementation fileTree(include: ['*.aar'], dir: 'libs')

Replace your code with following.

Open the top level ‘build.gradle’ file and add.

repositories {
        flatDir {
            dirs('/src/main/libs')
        }
    }

Then in your project’s build.gradle add the following.

api(name:'aar_module_name', ext:'aar')

I had the same issue, in the sense I wanted to encapsulate a library dependency into a module. However this library dependency had a bunch of aars and creating separate module each of them is just clutter, and can't even find that option in the new studio.

To resolve it I published the aar-s into my local maven, before starting the build process.

So my encapsulating module's build.gradle looked like this:

plugins {
  id 'com.android.library'
  id 'kotlin-android'
  id 'maven-publish'
}
//..
parent.allprojects { // for some reason simply repositories didn't work
  repositories {
    mavenLocal() 
  }
}
//...
publishing {
  publications {
    barOne(MavenPublication) {
        groupId 'foo-aar-dependency'
        artifactId 'bar1'
        version '1.0'
        artifact("$libsDirName/bar1.aar")
    }
    barTwo(MavenPublication) {
        groupId 'foo-aar-dependency'
        artifactId 'bar2'
        version '1.0'
        artifact("$libsDirName/bar2.aar")
    }
    barThree(MavenPublication) {
        groupId 'foo-aar-dependency'
        artifactId 'bar3'
        version '1.0'
        artifact("$libsDirName/bar3.aar")
    }
    // and so on...
  }
}

// add the publication before the build even starts
// used ./gradlew mymodule:assemble --dry-run to find where to put it
afterEvaluate {
  tasks.clean.dependsOn("publishToMavenLocal")
  tasks.preBuild.dependsOn("publishToMavenLocal")
}

dependencies {
  implementation "foo-aar-dependency:bar1:1.0"
  implementation "foo-aar-dependency:bar2:1.0"
  implementation "foo-aar-dependency:bar3:1.0"
  // and so on
  // also I had to make sure to add the aar's transitive dependencies as implementation below
}

Note: When I sync for the first time the dependencies are not found, but as soon as any clean/assemble is called the dependencies are published prior so it runs as it needs.

Note2: most of this can be moved into a separate file to not clutter your build.gradle

Note3: If you actually want to publish your module as a library this solution is not for you.

Note4: This also works on CI if you run clean then your next task.

It is bug in Android Studio 4.0.+.However, there is a solution.

First, project/build.gradle:

allprojects {
   repositories {
        google()
        jcenter()
        mavenCentral()
        flatDir {dirs "../MoudleA/aars,../MoudleB/aars,../MoudleC/libs".split(",")
        }
    }
}

Second, Moudle/build.gradle:

// MoudleA/build.gradle

repositories {
    flatDir {
        dirs 'aars'
    }
}

dependencies {
    api fileTree(dir: 'libs', include: ['*.jar'])
    //api fileTree(dir: 'aars', include: ['*.aar'])
    // aar
    new File('MoudleA/aars').traverse(
            nameFilter: ~/.*\.aar/
    ) { file ->
        def name = file.getName().replace('.aar', '')
        api(name: name, ext: 'aar')
    }
}

// MoudleB/build.gradle

repositories {
    flatDir {
        dirs 'aars'
    }
}

dependencies {
    api fileTree(dir: 'libs', include: ['*.jar'])
    //fullApi fileTree(dir: 'aars/full', include: ['*.aar'])
    //liteApi fileTree(dir: 'aars/lite', include: ['*.aar'])
    // aar
    new File('MoudleB/aars/full').traverse(
            nameFilter: ~/.*\.aar/
    ) { file ->
        def name = file.getName().replace('.aar', '')
        fullApi(name: 'full/' + name, ext: 'aar')
    }
    new File('MoudleB/aars/lite').traverse(
            nameFilter: ~/.*\.aar/
    ) { file ->
        def name = file.getName().replace('.aar', '')
        liteApi(name: 'lite/' + name, ext: 'aar')
    }

}

// MoudleC/build.gradle

repositories {
    flatDir {
        dirs 'libs'
    }
}

dependencies {
    //api fileTree(dir: 'libs', include: ['*.jar','*.aar'])
    api fileTree(dir: 'libs', include: ['*.jar'])
    // aar
    new File('MoudleC/libs').traverse(
            nameFilter: ~/.*\.aar/
    ) { file ->
        def name = file.getName().replace('.aar', '')
        api(name: name, ext: 'aar')
    }
}

It works for me，You can also try.

You can upload the AARs to an Artifactory, and consume them.

If you want to bundle a local .aar within your library and use that library in another project, you could take a look at "fat aars" https://github.com/kezong/fat-aar-android

EDIT : if the AAR does not contain android resources or native code, this could help you.

If you want this local resource directly linked to an "app" or "sdk" module (no compileOnly)

=> Use a jar.

• Rename the .aar to .zip
• Extract it
• Use the classes.jar inside

That's it.

Much lazier way to do this in build.gradle.kts files is to use a fileTree combined with flatDir repository.

repositories {
  flatDir {
    dir("$rootDir/libraries")
  }
}

dependencies {
   fileTree("$rootDir/libraries").forEach { file ->
        implementation(group = "", name = file.name.removeSuffix(".aar"), ext = "aar")
    }
}

This way when you add or remove deps to the folder they are automatically configured

In my case, I realised that I have created libs folder at wrong place then recreated folder in main folder and implementation fileTree(include: ['*.aar'], dir: 'libs') worked.

Adapt aar dependency to maven repo standards and depend on it.

Lets connect the dependency in build.gradle

repositories {
    maven { url "$project.projectDir/libs" }
}

dependencies {
    api "my-library-group:my-library-module:my-library-version"
}

Replace you libs/myLibrary.arr file with next files:

libs/my-library-group/my-library-module/my-library-version/my-library-module-my-library-version.aar
libs/my-library-group/my-library-module/my-library-version/my-library-module-my-library-version.pom
libs/my-library-group/my-library-module/maven-metadata-local.xml

Where my-library-module-my-library-version.aar is the original aar file

Content of my-library-module-my-library-version.pom

<?xml version="1.0" encoding="UTF-8"?>
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <modelVersion>4.0.0</modelVersion>
  <groupId>my-library-group</groupId>
  <artifactId>my-library-module</artifactId>
  <version>my-library-version</version>
  <packaging>aar</packaging>
</project>

Content of maven-metadata-local.xml

<?xml version="1.0" encoding="UTF-8"?>
<metadata>
  <groupId>my-library-group</groupId>
  <artifactId>my-library-module</artifactId>
  <versioning>
    <latest>my-library-version</latest>
    <release>my-library-version</release>
    <versions>
      <version>my-library-version</version>
    </versions>
    <lastUpdated>20211130111015</lastUpdated>
  </versioning>
</metadata>

Feel free to replace my-library-group, my-library-module, my-library-version with any value you like

I also hit this issue when I increase my Android plugin version to 4.0.1, and it turns to error, tried some solutions but none of them are actually doable in our project.
Since we are using product flavours, and different flavours are using different local aar file, we simply can not just using api(name: "xxx", ext: 'aar') since those aar files are located in different flatDir.
For now I have to roll back to previous gradle plugin version.
will edit this answer if I figure something out

for me works this solution: put into dependences in build.gradle:app file this string:

api fileTree(dir: 'libs', include: ['*.aar'])