Error: Couldnt find Gradle executable

[t-rhex]

`//START-OF-SCRIPT
node {
def server = Artifactory.server 'artifactory'

withCredentials([usernamePassword(credentialsId: 'artifactory',
                 usernameVariable: 'USERNAME', passwordVariable: 'PASSWORD')]) {
    server.username = "${USERNAME}"
    server.password = "${PASSWORD}"
}    

def rtGradle = Artifactory.newGradleBuild()
def buildInfo

stage ('Clone') {
    git url: 'https://github.com/cloudacademy/devops-webapp.git'
}

stage ('Artifactory Configuration') {
    rtGradle.tool = "gradle-5.6.4" // Tool name from Jenkins configuration
    rtGradle.deployer repo: 'gradle-release-local', server: server
    rtGradle.resolver repo: 'jcenter', server: server
}

stage ('Gradle Build') {
    buildInfo = rtGradle.run rootDir: "./", buildFile: 'build.gradle', tasks: 'clean build'
}

stage ('Gradle Publish') {
    buildInfo = rtGradle.run rootDir: "./", buildFile: 'build.gradle', tasks: 'artifactoryPublish'
}

stage ('Artifactory Publish Build Info') {
    server.publishBuildInfo buildInfo
}

}
//END-OF-SCRIPT`

I am having an issue with Gradle build. It says that Couldn't find Gradle executable. I have posted a screenshot below

[phihai222]

I got the same issue !!