[android] Failed to resolve: com.android.support:appcompat-v7:28.0

When I use com.android.support:appcompat-v7:28.+ in my project's build.gradle(module) it works without any error. But when I just use com.android.support:appcompat-v7:28, just without .+, it gives me an error:

Failed to resolve: com.android.support:appcompat-v7:28.0

Just without the .+ end of it. I added maven before but the result was the same. Any idea to solve it?

Add the following code on build.gragle (project) for adding Google maven repository

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

some guys who still might have the problem like me (FOR IRANIAN and all the coutries who have sanctions) , this is error can be fixed with proxy i used this free proxy for android studio 3.2 https://github.com/freedomofdevelopers/fod just to to Settings (Ctrl + Alt + S) and search HTTP proxy then check Manual proxy configuration then add fodev.org for host name and 8118 for Port number

As @Sourabh already pointed out, you can check in the Google Maven link what are the packages that Google has listed out.

If you, like me, are prompted with a similar message to this Failed to resolve: com.android.support:appcompat-v7:28.0, it could be that you got there after upgrading the targetSdkVersion or compileSdkVersion.

What is basically happening is that the package is not being found, as the message correctly says. If you upgraded the SDK, check the Google Maven, to check what are the available versions of the package for the new SDK version that you want to upgrade to.

I had these dependencies (on version 27):

implementation 'com.android.support:appcompat-v7:27.1.1'
implementation 'com.android.support:design:27.1.1'
implementation 'com.android.support:recyclerview-v7:27.1.1'
implementation 'com.android.support:cardview-v7:27.1.1'
implementation 'com.android.support:support-v4:27.1.1'

And I had to change the SDK version and the rest of the package number:

implementation 'com.android.support:appcompat-v7:28.0.0'
implementation 'com.android.support:design:28.0.0'
implementation 'com.android.support:recyclerview-v7:28.0.0'
implementation 'com.android.support:cardview-v7:28.0.0'
implementation 'com.android.support:support-v4:28.0.0'

Now the packages are found and downloaded. Since the only available package for the 28 version of the SDK is 28.0.0 at the moment of writing this.

Run

gradlew -q app:dependencies

It will remove what is wrong.

my problem was just network connection. using VPN solved the issue.

Ensure that your buildToolsVersion version tallies with your app compact version.

In order to find both installed compileSdkVersion and buildToolsVersion go to Tools > SDK Manager. This will pull up a window that will allow you to manage your compileSdkVersion and your buildToolsVersion.

To see the exact version breakdowns ensure you have the Show Package Details checkbox checked.

android {
    compileSdkVersion 28
    buildToolsVersion "28.0.3" (HERE)
    defaultConfig {
        applicationId "com.example.truecitizenquiz"
        minSdkVersion 14
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:28.0.0' (HERE)
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    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'
}

implementation 'com.android.support:appcompat-v7:28.0' implementation 'com.android.support:support-media-compat:28.0.0' implementation 'com.android.support:support-v4:28.0.0' All to add

in build.gradle , the version of bellow line should be same

implementation 'com.android.support:appcompat-v7:28.0.0-alpha1'
implementation 'com.android.support:design:28.0.0'