Android Studio 报错：Could not get unknown property ‘kotlin_version‘ for object of type_could not get unknown property 'kotlin_version' fo

导入项目，sync 的时候报错：

A problem occurred evaluating project ':app'.
> Could not get unknown property 'kotlin_version' for object of type org.gradle.api.internal.artifacts.dsl.dependencies.DefaultDependencyHandler.

出现这个问题，我的思路一般是：新建一个空项目，然后对比两个项目的配置文件。

我的问题是原来的app下build.gradle的dependencies 格式不对，

dependencies {
 
    implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
    implementation 'androidx.core:core-ktx:1.0.1'
    implementation 'androidx.appcompat:appcompat:1.2.0'
    implementation 'com.google.android.material:material:1.0.0'
    implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
    //testImplementation 'junit:junit:4.+'
    //androidTestImplementation 'androidx.test.ext:junit:1.1.2'
    //androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0'
}

改为如下就好了，

dependencies {
 
    implementation 'androidx.core:core-ktx:1.7.0'
    implementation 'androidx.appcompat:appcompat:1.3.0'
    implementation 'com.google.android.material:material:1.4.0'
    implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
    testImplementation 'junit:junit:4.13.2'
    androidTestImplementation 'androidx.test.ext:junit:1.1.3'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'
}