Conflict with dependency 'com.android.support:support-annotations' in project ':app'. Resolved versions for app (26.1.0) and test app (27.1.1) differ.

Question

I am new to Android App Development. When I tried to create a new project,Android Project...the following message popped up..

Error:Execution failed for task \':app:

Answer 1

A better solution is explained in the official explanation. I left the answer I have given before under the horizontal line.

According to the solution there:

Use an external tag and write down the following code below in the top-level build.gradle file. You're going to change the version to a variable rather than a static version number.

ext {
    compileSdkVersion = 26
    supportLibVersion = "27.1.1"
}

Change the static version numbers in your app-level build.gradle file, the one has (Module: app) near.

android {
    compileSdkVersion rootProject.ext.compileSdkVersion // It was 26 for example
    // the below lines will stay
}

// here there are some other stuff maybe

dependencies {
    implementation "com.android.support:appcompat-v7:${rootProject.ext.supportLibVersion}"
    // the below lines will stay
}

Sync your project and you'll get no errors.

---

You don't need to add anything to Gradle scripts. Install the necessary SDKs and the problem will be solved.

In your case, install the libraries below from Preferences > Android SDK or Tools > Android > SDK Manager