Gradle: Could not get unknown property 'classesDir' for main classes - gradle

Question

According to the documentation, I've tried to use aspectj plugin.
This is the message I get when I build my project.
FAILURE: Build failed with an exception.
* Where:
Build file '/home/jesudi/projects/gradle-vscode/build.gradle' line: 22
* What went wrong:
A problem occurred evaluating root project 'security'.
> Failed to apply plugin [id 'aspectj.gradle']
> Could not create task ':compileAspect'.
> Could not get unknown property 'classesDir' for main classes of type org.gradle.api.internal.tasks.DefaultSourceSetOutput.
This is my script:
buildscript {
repositories {
mavenCentral()
maven {
url "https://plugins.gradle.org/m2/"
}
}
dependencies {
classpath "org.apache.meecrowave:meecrowave-gradle-plugin:1.2.6"
classpath "gradle.plugin.aspectj:gradle-aspectj:0.1.6"
}
}
plugins {
id 'java'
}
project.ext {
aspectjVersion = '1.9.2'
}
apply plugin: 'aspectj.gradle'
apply plugin: "org.apache.microwave.microwave"
java {
sourceCompatibility = JavaVersion.VERSION_11
targetCompatibility = JavaVersion.VERSION_11
}
dependencies {
compile("org.apache.meecrowave:meecrowave-core:1.2.6")
compile("org.apache.meecrowave:meecrowave-specs-api:1.2.6")
}
meecrowave {
httpPort = 9090
// most of the meecrowave core configuration
}
This is the gradle -version output:
------------------------------------------------------------
Gradle 5.1.1
------------------------------------------------------------
Build time: 2019-01-10 23:05:02 UTC
Revision: 3c9abb645fb83932c44e8610642393ad62116807
Kotlin DSL: 1.1.1
Kotlin: 1.3.11
Groovy: 2.5.4
Ant: Apache Ant(TM) version 1.9.13 compiled on July 10 2018
JVM: 11.0.2 (Oracle Corporation 11.0.2+9)
OS: Linux 4.15.0-20-generic amd64

Answer 1

In Gradle 5.x, this property has been renamed to classesDirs from classesDir.
You can find more information here

Answer 2

Possible your plugin is not a root of problem but the version of Gradle is.
First time I had the same error in libgdx game (android studio).
In build.gradle(desktop) file "classDir was renamed to classesDirs and it helped.
from files(sourceSets.main.output.classesDirs)

Answer 3

The classesDir property was deprecated in gradle 4.x, and removed in gradle 5.x (see the release notes).
The plugin has apparently not been maintained.

Answer 4

I got a similar error message, not with this plugin but even with the HelloWorld app created by Grails (3.2.9). In my case, I already used sdkman to set my current Gradle to 3.5 instead of 5, but the problem persists. It turned out that the "grails" cli (https://github.com/grails/grails-core/blob/3.2.x/grails-shell/src/main/groovy/org/grails/cli/gradle/GradleUtil.groovy) uses the default sdkman version for Gradle (which is different from the "current" version).
From Grails 3.3.X, one can set "gradleWrapperVersion=3.5" in gradle.properties instead, or use GRAILS_GRADLE_HOME environment variable as before.