Android Studio Gradle Build failing - asking for a sdk version that doesn't exist

Question

24 hours ago my project built perfectly, no errors. Without changing a single piece of code, it will no longer build when I have resumed work. Checking out to older working commits now produces the same error.

These are the error codes I get:

Information:Gradle tasks [assemble]
Error:(9, 5) error: resource android:attr/dialogCornerRadius not found.
/home/liam/.gradle/caches/transforms-1/files-1.1/appcompat-v7-28.0.0-alpha1.aar/536e4dd78846259cf8bef0fd6a3ea0e6/res/values/values.xml

I think that this has been caused by Android P being released and my Android Studio automatically upgrading or something like that. Which would explain why old commits that worked get this same error. This would be a very new issue, which would explain why I cannot find a solution to it yet.

Searching these error codes leads to a similar issue that was resolved by changing the SDK version in the gradle build file. My problem differs from this because changing to SDK 28 (I'm pretty sure 28 doesn't even exist) leads to android studio saying this package isn't available/doesn't exist for download.

How to find issue Android SDK 3.0 Error:(9, 5) error: resource android:attr/colorError not found

Clicking on the first mentioned error codes leads to a file called v28/values-v28.xml being opened.

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <style name="Base.Theme.AppCompat" parent="Base.V28.Theme.AppCompat"/>
    <style name="Base.Theme.AppCompat.Light" parent="Base.V28.Theme.AppCompat.Light"/>
    <style name="Base.V28.Theme.AppCompat" parent="Base.V26.Theme.AppCompat">
        <!-- We can use the platform styles on API 28+ -->
        <item name="dialogCornerRadius">?android:attr/dialogCornerRadius</item>
    </style>
    <style name="Base.V28.Theme.AppCompat.Light" parent="Base.V26.Theme.AppCompat.Light">
        <!-- We can use the platform styles on API 28+ -->
        <item name="dialogCornerRadius">?android:attr/dialogCornerRadius</item>
    </style>
</resources>

Here are my gradle files:

apply plugin: 'com.android.application'

android {
    compileSdkVersion 26
    defaultConfig {
        applicationId "com.timelord.timelord.timelord"
        minSdkVersion 24
        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-v7:26.1.0'
    implementation 'com.android.support:design:+'
    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'
    implementation files('libs/joda-time-2.9.9.jar')
}

And

// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {

    repositories {
        google()
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.0.1'


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

allprojects {
    repositories {
        google()
        jcenter()
    }
}

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

Answer 1

You have the design lib version with + in your build.gradle which means it will download the latest version. So please set it to 26.1.0 and it should work. The support 28 is in alpha and was released yesterday with the new android P preview