title: Flutter error - Gradle task assembleDebug failed with exit code -1
body: <p>I'm new to flutter. I just created a new project in flutter and have not even altered the code.
  And when I run the code I get the following error.</p>
  
  <pre><code>Launching lib\main.dart on SM A750F in debug mode...
  Gradle task assembleDebug failed with exit code -1
  Exited (sigterm)
  </code></pre>
  
  <p>I have no idea how to fix this, searched a number of ways</p>
  
  <p>When I run flutter doctor I get this error,</p>
  
  <pre><code>Android toolchain - develop for Android devices (Android SDK version 29.0.2)
      X Android license status unknown.
        Try re-installing or updating your Android SDK Manager.
        See https://developer.android.com/studio/#downloads or visit https://flutter.dev/setup/#android-setup for detailed instructions.
  </code></pre>
  
  <p>I dont know if this has got anything to do with the error above.</p>
  
  <p>build.gradle(app) </p>
  
  <pre><code>def localProperties = new Properties()
  def localPropertiesFile = rootProject.file('local.properties')
  if (localPropertiesFile.exists()) {
      localPropertiesFile.withReader('UTF-8') { reader -&gt;
          localProperties.load(reader)
      }
  }
  
  def flutterRoot = localProperties.getProperty('flutter.sdk')
  if (flutterRoot == null) {
      throw new GradleException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
  }
  
  def flutterVersionCode = localProperties.getProperty('flutter.versionCode')
  if (flutterVersionCode == null) {
      flutterVersionCode = '1'
  }
  
  def flutterVersionName = localProperties.getProperty('flutter.versionName')
  if (flutterVersionName == null) {
      flutterVersionName = '1.0'
  }
  
  apply plugin: 'com.android.application'
  apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"
  
  android {
      compileSdkVersion 28
  
      lintOptions {
          disable 'InvalidPackage'
      }
  
      defaultConfig {
          // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
          applicationId "com.dev.teamo"
          minSdkVersion 16
          targetSdkVersion 28
          versionCode flutterVersionCode.toInteger()
          versionName flutterVersionName
          testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
      }
  
      buildTypes {
          release {
              // TODO: Add your own signing config for the release build.
              // Signing with the debug keys for now, so `flutter run --release` works.
              signingConfig signingConfigs.debug
          }
      }
  }
  
  flutter {
      source '../..'
  }
  
  dependencies {
      testImplementation 'junit:junit:4.12'
      androidTestImplementation 'androidx.test:runner:1.1.1'
      androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.1'
  }
  </code></pre>
  
  <p>Thanks in advance</p>