title: Release APK not working for API 6.0 and below
body: <p>I just build a release APK and tried it. It works fine in all the devices that is having API of 7.0 or high. But when I tried testing it in marshmallow or devices with lower API than marshmallow, then the apk was not installed. It showed the error message App not installed. I have my minSdkVersion as 21 but still this problem happens.</p>
  
  <p>This is my build.gradle:</p>
  
  <pre><code>apply plugin: 'com.android.application'
  apply plugin: 'com.apollographql.android'
  apply plugin: 'kotlin-android'
  
  apply plugin: 'kotlin-android-extensions'
  
  android {
  compileSdkVersion 28
  defaultConfig {
      applicationId "com.example.leadershipboard"
      minSdkVersion 21
      targetSdkVersion 28
      versionCode 1
      versionName "1.0"
      testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
  }
  buildTypes {
      release {
          minifyEnabled false
          proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
      }
   }
  }
  
  dependencies {
       implementation fileTree(dir: 'libs', include: ['*.jar'])
       implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
       implementation 'androidx.appcompat:appcompat:1.0.0-beta01'
       implementation 'androidx.core:core-ktx:1.0.0-rc02'
       implementation 'com.apollographql.apollo:apollo-runtime:0.4.2'
       implementation 'com.squareup.okhttp3:logging-interceptor:3.8.1'
       implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
       implementation 'com.google.android.material:material:1.0.0'
       testImplementation 'junit:junit:4.12'
       androidTestImplementation 'androidx.test:runner:1.1.0-alpha4'
       androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.0-alpha4'
  }
  </code></pre>
  
  <p>Also While generating the signed APK I ticked both V1 and V2 checkboxes. Since I saw that in a solution but that didn't work.</p>
  
  <p>What is the problem here and how can I resolve this?</p>
  
  <p>Thanks in advance.</p>