Unable to resolve dependencies in Android Studio 3.2.1

Question

I have been getting unable to resolve dependencies error after updating the gradle to 5.1.1. I have tried all the possible solutions in this thread and this one as well. But couldn't fix my problem.

This is my error log :

Unable to resolve dependency for ':app@debug/compileClasspath': Could not resolve com.android.support:appcompat-v7:28.0.0.
Unable to resolve dependency for ':app@debug/compileClasspath': Could not resolve com.android.support.constraint:constraint-layout:1.1.3.
Unable to resolve dependency for ':app@debug/compileClasspath': Could not resolve com.android.support:design:28.0.0.
Unable to resolve dependency for ':app@debugAndroidTest/compileClasspath': Could not resolve com.android.support.test:runner:1.0.2.
Unable to resolve dependency for ':app@debugAndroidTest/compileClasspath': Could not resolve com.android.support.test.espresso:espresso-core:3.0.2.
Unable to resolve dependency for ':app@debugAndroidTest/compileClasspath': Could not resolve com.android.support:appcompat-v7:28.0.0.
Unable to resolve dependency for ':app@debugAndroidTest/compileClasspath': Could not resolve com.android.support.constraint:constraint-layout:1.1.3.
Unable to resolve dependency for ':app@debugAndroidTest/compileClasspath': Could not resolve com.android.support:design:28.0.0.
Unable to resolve dependency for ':app@debugUnitTest/compileClasspath': Could not resolve com.android.support:appcompat-v7:28.0.0.
Unable to resolve dependency for ':app@debugUnitTest/compileClasspath': Could not resolve com.android.support.constraint:constraint-layout:1.1.3.
Unable to resolve dependency for ':app@debugUnitTest/compileClasspath': Could not resolve com.android.support:design:28.0.0.
Unable to resolve dependency for ':app@release/compileClasspath': Could not resolve com.android.support:appcompat-v7:28.0.0.
Unable to resolve dependency for ':app@release/compileClasspath': Could not resolve com.android.support.constraint:constraint-layout:1.1.3.
Unable to resolve dependency for ':app@release/compileClasspath': Could not resolve com.android.support:design:28.0.0.
Unable to resolve dependency for ':app@releaseUnitTest/compileClasspath': Could not resolve com.android.support:appcompat-v7:28.0.0.
Unable to resolve dependency for ':app@releaseUnitTest/compileClasspath': Could not resolve com.android.support.constraint:constraint-layout:1.1.3.
Unable to resolve dependency for ':app@releaseUnitTest/compileClasspath': Could not resolve com.android.support:design:28.0.0.

And this is app level build.gradle file

apply plugin: 'com.android.application'

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "com.project.FirstApplication"
        minSdkVersion 15
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    implementation 'com.android.support:design:28.0.0'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
}

This is project's build.gradle

buildscript {

    repositories {
        google()
        jcenter()
        maven {
            url "https://maven.google.com"
        }
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.2.1'


        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        google()
        jcenter()
        maven {
            url "https://maven.google.com"
        }
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

Regards

Answer 1

For me the reason was I am working in a restricted area. So there was blocking of files being downloaded. And some how the gradle was not able to download all the dependencies. I just ran everything in open internet connectivity and it all works like a charm.

So I followed this thread to allow the packages to be downloaded in the restricted environment. Still if it didn't resolve your issue if you are working in a restricted environment contact your network guy.

Answer 2

You need classpath 'com.android.tools.build:gradle:3.3.0', according to this for gradle 5.1.1.

I don't agree with tips from Deepak with putting google() last. Historically I need it first due to other problems.

Also, your implementation 'com.android.support:appcompat-v7:28.0.0' is redundant due to already having implementation 'com.android.support:design:28.0.0'.

According to this you can remove

maven { url "https://maven.google.com" }

as well.

Answer 3

In you project level Gradle change google() position like my example.

buildscript {
    repositories {
        jcenter()
        maven {
            url 'https://maven.fabric.io/public'
        }
        maven {
            url 'https://maven.google.com/'
            name 'Google'
        }
        google()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.1.2'
        classpath 'com.google.gms:google-services:3.2.1'
        classpath 'io.fabric.tools:gradle:1.25.4'


        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}