The following options were not recognized by any processor: '[kapt.kotlin.generated, room.incremental]'

Question

:app:kaptDebugKotlin
w: warning: The following options were not recognized by any processor: '[kapt.kotlin.generated, room.incremental]'

Why am I getting this? I am using Room in a multi module project.

• Kotlin version: 1.3.50
• AGP: 3.5.0
• Room: 2.2.0-rc01

Shared libraries module: api "androidx.room:room-runtime:$room_version" api "androidx.room:room-ktx:$room_version" api "androidx.room:room-rxjava2:$room_version"

App module:

kapt "androidx.room:room-compiler:$room_version"

Gradle.properties

kapt.incremental.apt=true

Build.gradle defaultConfig includes these compile options:

javaCompileOptions {
        annotationProcessorOptions {
            arguments = ["room.incremental":"true"]
        }
    }

Answer 1

While I agree that missing kapt in module was the original problem in IDE.

• "androidx.room:room-compiler:${roomVersion}"

There can be other one in CLI, which you can see with verbose warnings:

Current JDK version 1.8.0_191-8u191-b12-2ubuntu0.18.04.1-b12 has a bug (https://bugs.openjdk.java.net/browse/JDK-8007720) that prevents Room from being incremental. Consider using JDK 11+ or the embedded JDK shipped with Android Studio 3.5+.warning: The following options were not recognized by any processor: '[kapt.kotlin.generated, room.incremental]'[WARN] Incremental annotation processing requested, but support is disabled because the following processors are not incremental: androidx.room.RoomProcessor (DYNAMIC).

Answer 2

This type of problem can occure with a multi-module project that has been added to room. For such a project the problem was caused by adding the RoomDatabase derived class to a library module, but configuring the build.gradle of app module.

The solution is to configure the build.gradle of the module that contains the RoomDatabase derived class.

• In the build.gradle file in the dependencies{} section add the dependency for the room compiler.

kapt "android.arch.persistence.room:compiler:$room_version"

Note that for java based project use below code

annotationProcessor "android.arch.persistence.room:compiler:$room_version"