selamlar;

ERROR: Cannot get property 'compileSdkVersion' on extra properties extension as it does not exist

hatasını almaktayım.

Gradle kodum ise ;

apply plugin: 'com.android.application'


buildscript{
repositories{
jcenter()
google()
}

dependencies{
classpath 'com.android.tools.build:gradle:3.1.1'
}
}

android {
compileSdkVersion rootProject.ext.compileSdkVersion
buildToolsVersion rootProject.ext.buildToolsVersion

defaultConfig {
applicationId "com.topjohnwu.magisk"
minSdkVersion 21
targetSdkVersion rootProject.ext.compileSdkVersion
javaCompileOptions {
annotationProcessorOptions {
argument('butterknife.debuggable', 'false')
}
}
}

buildTypes {
release {
minifyEnabled true
shrinkResources true
proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
}
}

flavorDimensions "mode"

productFlavors {
full {
versionCode 127
versionName "5.8.1"
}
stub {
versionCode 1
versionName "stub"
}
}

compileOptions {
sourceCompatibility JavaVersion.VERSION_1_8
targetCompatibility JavaVersion.VERSION_1_8
}
dexOptions {
preDexLibraries true
javaMaxHeapSize "2g"
}
lintOptions {
disable 'MissingTranslation'
}
}

dependencies {
implementation fileTree(include: ['*.jar'], dir: 'libs')
fullImplementation project(':utils')
implementation "com.android.support:support-core-utils:${rootProject.ext.supportLibVersion}"
fullImplementation "com.android.support:preference-v7:${rootProject.ext.supportLibVersion}"
fullImplementation "com.android.support:recyclerview-v7:${rootProject.ext.supportLibVersion}"
fullImplementation "com.android.support:cardview-v7:${rootProject.ext.supportLibVersion}"
fullImplementation "com.android.support:design:${rootProject.ext.supportLibVersion}"
fullImplementation 'com.github.topjohnwu:libsu:1.3.0'
fullImplementation 'com.atlassian.commonmark:commonmark:0.11.0'
fullImplementation 'org.kamranzafar:jtar:2.3'
fullImplementation 'com.jakewharton:butterknife:8.8.1'
annotationProcessor 'com.jakewharton:butterknife-compiler:8.8.1'
}

lütfen yardım edin !