Default interface methods are only supported starting with Android N

Question

I upgraded to android studio 3 1 and I m getting the following error  Default interface methods are only supported starting with Android N  --min-api 24   void android arch lifecycle DefaultLifecycleObserver onCreate android arch lifecycle LifecycleOwner  Message kind ERROR  text Default interface methods are only supported starting with Android N  --min-api 24   void android arch lifecycle DefaultLifecycleObserver onCreate android arch lifecycle LifecycleOwner   sources  Unknown source file   tool name Optional of D8     Here is my gradle config  compileSdkVersion 27   buildToolsVersion  27 0 3  defaultConfig       minSdkVersion 16     targetSdkVersion 27      multiDexEnabled true                  As you can see  I am targeting 27 which is already ahead of 24 that it s complaining about  What exactly should I do to fix this  If I change to 1 8 java  won t I be missing a lot of customers  Why was I not getting this error before I upgraded Android Studio  I do not know if this is about the LifecycleObserver class I recently put in  it was in Kotlin and now I changed it to java but still get the same error after cleaning project  public class LifeCycleAwareObserver implements LifecycleObserver         OnLifecycleEvent Lifecycle Event ON STOP      public void  onAppBackgrounded             AnalyticsUtils trackStartSession true               OnLifecycleEvent Lifecycle Event ON START      public void onAppForegrounded             AnalyticsUtils trackStartSession false            How to trace where the error is coming from so I can fix it  Here are my version dependencies  project ext                  firebase version    12 0 0           supportlib version    27 0 2           room version    1 0 0           espresso version    3 0 1           archLifecycleVersion    1 1 1

User · Answer

Update your build gradle Module app  add compileOptions block and add JavaVersion VERSION 1 8  apply plugin   com android application   android                                                           compileOptions           sourceCompatibility JavaVersion VERSION 1 8         targetCompatibility JavaVersion VERSION 1 8

User · Answer

Use this code in your build gradle  android       compileOptions           incremental true         sourceCompatibility JavaVersion VERSION 1 8         targetCompatibility JavaVersion VERSION 1 8

User · Answer

As CommonsWare mentioned  for reference add this inside the android       closure in the build gradle for your app module to resolve issue     android         compileOptions           sourceCompatibility JavaVersion VERSION 1 8         targetCompatibility JavaVersion VERSION 1 8

User · Answer

In app-level gradle  you have to write these code  android         compileOptions       sourceCompatibility JavaVersion VERSION 1 8     targetCompatibility JavaVersion VERSION 1 8        They come from JavaVersion java in Android   An enumeration of Java versions  Before 9  http   www oracle com technetwork java javase versioning-naming-139433 html After 9  http   openjdk java net jeps 223   canerkaseler

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apply plugin   com android application  apply plugin   kotlin-android  apply plugin   kotlin-android-extensions    android   compileSdkVersion 30 buildToolsVersion  quot 30 0 0 quot   compileOptions       sourceCompatibility JavaVersion VERSION 1 8     targetCompatibility JavaVersion VERSION 1 8    defaultConfig       applicationId  quot com example architecture quot      minSdkVersion 16     targetSdkVersion 30     versionCode 1     versionName  quot 1 0 quot       testInstrumentationRunner  quot androidx test runner AndroidJUnitRunner quot     buildTypes       release           minifyEnabled false         proguardFiles getDefaultProguardFile  proguard-android-optimize txt     proguard-rules pro               dependencies    implementation  androidx room room-runtime 2 2 5  implementation  androidx lifecycle lifecycle-extensions 2 2 0  annotationProcessor  androidx room room-compiler 2 2 5  def lifecycle version    quot 2 2 0 quot  def arch version    quot 2 1 0 quot   implementation fileTree dir   quot libs quot   include    quot   jar quot    implementation  quot org jetbrains kotlin kotlin-stdlib  kotlin version quot  implementation  androidx core core-ktx 1 3 0  implementation  androidx appcompat appcompat 1 1 0  implementation  androidx constraintlayout constraintlayout 1 1 3  testImplementation  junit junit 4 12  androidTestImplementation  androidx test ext junit 1 1 1  androidTestImplementation  androidx test espresso espresso-core 3 2 0  implementation  quot androidx lifecycle lifecycle-viewmodel-savedstate  lifecycle version quot  implementation  quot androidx lifecycle lifecycle-common-java8  lifecycle version quot  implementation  quot androidx lifecycle lifecycle-service  lifecycle version quot  implementation  quot androidx lifecycle lifecycle-process  lifecycle version quot  implementation  quot androidx cardview cardview 1 0 0 quot      Add the configuration in your app module s build gradle android               compileOptions           sourceCompatibility JavaVersion VERSION 1 8         targetCompatibility JavaVersion VERSION 1 8

User · Answer

You can resolve this issue by downgrading Source Compatibility and Target Compatibility Java Version to 1 8 in Latest Android Studio Version 3 4 1   Open Module Settings  Project Structure  Winodw by right clicking on app folder or Command   Down Arrow on Mac  Go to Modules -  Properties  Change Source Compatibility and Target Compatibility Version to 1 8  Click on Apply or OK Thats it  It will solve your issue    Also you can manually add in build gradle  Module  app    android        compileOptions           sourceCompatibility    1 8          targetCompatibility    1 8

User · Answer

This also happened to me but using Dynamic Features  I already had Java 8 compatibility enabled in the app module but I had to add this compatibility lines to the Dynamic Feature module and then it worked

User · Answer

You should use Java 8 to solve this  based on the Android documentation you can do this by clicking File  gt  Project Structure and change Source Compatibility and Target Compatibility   and you can also configure it directly in the app-level build gradle file  android              Configure only for each module that uses Java 8      language features  either in its source code or      through dependencies     compileOptions       sourceCompatibility JavaVersion VERSION 1 8     targetCompatibility JavaVersion VERSION 1 8

User · Answer

Setting the minSdkVersion to 21 from 19 solved the issue for me   defaultConfig           applicationId  com example          minSdkVersion 21         targetSdkVersion 29         versionCode 23         versionName  1 0          vectorDrawables useSupportLibrary   true

User · Answer

My project use ButterKnife and Retro lambda  setting JavaVersion VERSION 1 8 will not work  It always blames at ButterKnife static interface function until I found this Migrate from Retrolambda  TL DR  Just add JavaVersion VERSION 1 8 and completely REMOVE retrolambda from your project  It will build successfully

[android] Default interface methods are only supported starting with Android N

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