An API level of 31 is not supported by this compiler. Please use an API level of 30 or earlier

Question

I upgrade existing android project to API level 31. I use Java as the language. I changed the build.gradle

compileSdkVersion 31
defaultConfig {
    applicationId 'com.app.app'
    minSdkVersion 16
    targetSdkVersion 31
    versionCode 91
    versionName '4.0.1'
    testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    multiDexEnabled true
}

But I couldn't debug the app using an AVD or a real device. I am getting this error.

> Task :app:mergeProjectDexDebug
AGPBI: {"kind":"warning","text":"An API level of 31 is not supported by this compiler. Please use an API level of 30 or earlier","sources":[{}],"tool":"D8"}
AGPBI: {"kind":"warning","text":"An API level of 31 is not supported by this compiler. Please use an API level of 30 or earlier","sources":[{}],"tool":"D8"}
AGPBI: {"kind":"warning","text":"An API level of 31 is not supported by this compiler. Please use an API level of 30 or earlier","sources":[{}],"tool":"D8"}
AGPBI: {"kind":"warning","text":"An API level of 31 is not supported by this compiler. Please use an API level of 30 or earlier","sources":[{}],"tool":"D8"}
AGPBI: {"kind":"warning","text":"An API level of 31 is not supported by this compiler. Please use an API level of 30 or earlier","sources":[{}],"tool":"D8"}
AGPBI: {"kind":"warning","text":"An API level of 31 is not supported by this compiler. Please use an API level of 30 or earlier","sources":[{}],"tool":"D8"}
AGPBI: {"kind":"warning","text":"An API level of 31 is not supported by this compiler. Please use an API level of 30 or earlier","sources":[{}],"tool":"D8"}
AGPBI: {"kind":"warning","text":"An API level of 31 is not supported by this compiler. Please use an API level of 30 or earlier","sources":[{}],"tool":"D8"}
AGPBI: {"kind":"warning","text":"An API level of 31 is not supported by this compiler. Please use an API level of 30 or earlier","sources":[{}],"tool":"D8"}
An API level of 31 is not supported by this compiler. Please use an API level of 30 or earlier

I think I need to update the compiler, How can I do that?

Answer 1

Try adding this to your build.gradle file:

android {
  ...
  compileOptions {
    sourceCompatibility JavaVersion.VERSION_1_8
    targetCompatibility JavaVersion.VERSION_1_8
  }
  kotlinOptions {
    jvmTarget = '1.8'
  }
}