Gradle build fails due to lint classpath error on Android

In my case this error was triggered because ANDROID_HOME environment variable wasn't set

The cause of this issue is that Gradle can't find the Android SDK. There are several ways to fix it:

Define the ANDROID_HOME environment variable

ANDROID_HOME=your/path/to/android/sdk; export ANDROID_HOME

or Add sdk.dir to the file local.properties, for example on my Linux computer

sdk.dir=/home/sdeng/Android/Sdk

If you already defined ANDROID_HOME or sdk.dir, it still happens. Its probably something is wrong with the specific version of your Android SDK or Gradle daemon. Try to kill all Gradle processes, re-download the specific version of Android SDK.

Or you can check the SDK at directory $ANDROID_HOME/platforms/android-28, where 28 is the compileSdkVersion defined in build.gradle

I have figured out what the problem is. I use the build parameter 'dev' (Pbuild=dev) to make sure that the CI (Travis, in this case) uses the mock version of my google-services.json file placed in the app/src/dev folder. However, I forgot to configure the 'dev' build variant in the build.gradle files of my modules.

Solution is to add the dev build type in all modules, like this:

build.gradle

android {
  ...

  buildTypes {
    release {
      ...
    }
    debug {
      ...
    }
    dev {
      minifyEnabled false
      proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
    }
}

Please note that you will have to do this for all the modules in your project.