android studio 3.4.1 and google admob change

In build.gradle (Module:app) change
...
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
...
dependencies {

   implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    implementation 'com.google.android.gms:play-services-ads:17.2.1'

In AndroidManifest.xml add

<manifest>
    <application>
        ...
        <meta-data
            android:name="com.google.android.gms.ads.AD_MANAGER_APP"
            android:value="true"/>
    </application>
</manifest>

defender locking bignox virtual disk

windows defender sometimes open file in background process, to scan for malicious code. If defender (or other antivirus) open bignox virtual disk it will lock it and cause your emulator crash. You need to exclude virtual disk that used by bignox. Here are the steps you need to do:

1. Open your windows defender (or your antivirus)
2. Go to setting "Virus & thread protection settings"
3. in "Exclusions" click "Add or remove exclusions"
4. Click "Add an exclusion" and choose "File type"
5. in "Enter extension" box type "vmdk"
6. repeat step 4 for file type "vbox" and "vdi"

You may want to increase your emulator by excluding these files:

1. C:\Program Files (x86)\Bignox\BigNoxVM\RT\NoxVMSVC.exe
2. C:\Program Files (x86)\Nox\bin\Nox.exe