Error:Unable to resolve dependency for ':app@debugAndroidTest/compileClasspath':No cached version available for offline mode?

Question

I was already activated offline mode in the android studio. The main problem is that Project Sync failed.

These are the my dependencies

 apply plugin: 'com.android.application' android { compileSdkVersion 26 defaultConfig { applicationId "com.example.starcom.practicemp3audio" minSdkVersion 15 targetSdkVersion 26 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-v7:26.0.0-beta1' implementation 'com.android.support.constraint:constraint-layout:1.0.2' testImplementation 'junit:junit:4.12' androidTestImplementation 'com.android.support.test:runner:1.0.1' androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'

These are my Gradle sync

 Error:Unable to resolve dependency for ':app@debug/compileClasspath': Could not resolve com.android.support:appcompat-v7:26.0.0-beta1.

 Error:Unable to resolve dependency for ':app@debugAndroidTest/compileClasspath': Could not download support-annotations.jar (com.android.support:support-annotations:25.4.0): No cached version available for offline mode

Answer 1

When I consult to my mentor they simply remove -beta1 from my dependencies

 Before implementation 'com.android.support:appcompat-v7:26.0.0-beta1' After implementation 'com.android.support:appcompat-v7:26.0.0'

And "Sync" once again problem has been resolved.