I tried File -> Invalidate caches\Restart, that didn't help me.
Log:
16:05   Gradle sync started
16:05   Gradle sync failed: Plugin with id 'com.android.application' not found.
            Consult IDE log for more details (Help | Show Log) (34s 987ms)
build.gradle application
apply plugin: 'com.android.application'
buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:2.1.2'
    }
}
allprojects {
    repositories {
        jcenter()
    }
}
android {
    compileSdkVersion 27
    buildToolsVersion "27.0.1"
    defaultConfig {
        applicationId "ru.startandroid.androidlessons"
        minSdkVersion 15
        targetSdkVersion 27
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}
dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    compile 'com.android.support:appcompat-v7:27.+'
    compile 'com.android.support.constraint:constraint-layout:1.0.2'
    testCompile 'junit:junit:4.12'
}
 
     
     
    