error while exporting grails 2 plugin to grails 3

may help you . I have a multi-project gradle build that has several Grails app. One of these app contains many artefacts (controllers, services, groovy code, etc...). , Add the following lines to the begin of your gradle.build

import org.grails.gradle.plugin.GrailsTask

tasks.withType(org.grails.gradle.plugin.GrailsTask) { Task t ->
    t.jvmOptions {
        jvmArgs '-Xms32m -Xmx1524m -XX:PermSize=32m -XX:MaxPermSize=512m -XX:+UseCompressedOops -XX:+UseConcMarkSweepGC -XX:+UseParNewGC'.split(' ')
    }
}

I wish this help you Running application without forking fixed the problem.
Simply add this line to BuildConfig.groovy

grails.project.fork.run=false

hope this fix your issue The behavior is caused by a bug in grails 2.3.8 (http://jira.grails.org/browse/GRAILS-11360)
A workaround is to include the following line of config in the BuildConfig.groovy

grails.project.work.dir = "target/work"

seems to work fine With Grails 2.4.0 you don't need to make any mention of Spock in BuildConfig.groovy. See the sample project at https://github.com/jeffbrown/spockdemo.
When you can, you should look at upgrading to the latest in the 2.4.x line. A number of issues have been addressed since 2.4.0 was released.

will help you Whenever I enter the grails command: test-app I get this error: , for Grails 2.2+ try this code in your BuildConfig:

grails.project.dependency.resolution = {
  repositories {
    grailsCentral()
    mavenCentral()
  }
  dependencies {
    test "org.spockframework:spock-grails-support:0.7-groovy-2.0"
  }
  plugins {
    test(":spock:0.7") {
      exclude "spock-grails-support"
    }
  }
}