How to fix 'ERROR: Failed to resolve: androidx'?

Question

i back to work again to complete my application but when the application start syncing it gave me

Failed to resolve: androidx Affected Modules: href="openFile:D:/.android/Step View/Application/Source Code/app/build.gradle">app

I see a question like this but it didn't works for me. sorry for my bad english.

this is my gradle. app

buildscript {
    repositories {
        maven { url 'https://plugins.gradle.org/m2/' }
    }
    dependencies {
        classpath 'gradle.plugin.com.onesignal:onesignal-gradle-plugin:[0.11.0, 0.99.99]'
    }
}
apply plugin: 'com.onesignal.androidsdk.onesignal-gradle-plugin'

repositories {
    maven {
        url 'https://maven.google.com'
    }
}

apply plugin: 'com.android.application'

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "com.xcoder.stepview"
        minSdkVersion 17
        targetSdkVersion 28
        multiDexEnabled true
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "androidx.connection_light.runner.AndroidJUnitRunner"
        manifestPlaceholders = [
                onesignal_app_id               : '6a2c7692-81ec-4d12-b973-6b78f71f380e',
                // Project number pulled from dashboard, local value is ignored.
                onesignal_google_project_number: 'REMOTE'
        ]
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
    buildToolsVersion '28.0.3'
}

dependencies {
    implementation fileTree(include: ['*.jar'], dir: 'libs')
    implementation 'androidx.appcompat:appcompat:1.1.0-alpha01'
    implementation 'com.google.firebase:firebase-core:16.0.6'
    implementation 'com.android.support:multidex:1.0.3'
    implementation 'com.github.kittinunf.fuel:fuel-android:1.12.1'
    implementation 'com.google.firebase:firebase-ads:17.1.2'
    implementation 'com.github.bassaer:chatmessageview:1.10.0'
    implementation 'androidx.constraintlayout:constraintlayout:2.0.0-alpha3'
    implementation 'com.github.markushi:circlebutton:1.1'
    implementation 'com.google.android.material:material:1.1.0-alpha02'
    implementation 'com.google.firebase:firebase-database:16.0.5'
    implementation 'com.github.ybq:Android-SpinKit:1.2.0'
    implementation 'androidx.cardview:cardview:1.0.0'
    implementation 'commons-io:commons-io:2.5'
    implementation 'androidx.percentlayout:percentlayout:1.0.0'
    implementation 'com.onesignal:OneSignal:[3.9.1, 3.99.99]'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'androidx.connection_light:runner:1.1.1'
    androidTestImplementation 'androidx.connection_light.espresso:espresso-core:3.1.1'
}

apply plugin: 'com.google.gms.google-services'

Solution

In my case it was caused by a typo in build.gradle:

//androidTestImplementation 'androidx  .test.espresso:espresso-core:3.2.0' // wrong!
androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'

I found the error by running the Gradle wrapper from the command line with the stacktrace option:

./gradlew clean build --stacktrace

Output:

Caused by: org.gradle.internal.resolve.ModuleVersionNotFoundException: Could not find androidx. test.espresso:espresso-core:3.2.0.