title: Getting "package android.support.multidex does not exist" after upgrading to Android Studio 2.3
body: <p>I updated from Android  Studio 2.2.3 to Android Studio 2.3 yesterday, and I ran into the following two problems:</p>
  
  <ul>
  <li><p>Upon updating, Gradle 3.2 was installed by default, but syncing my
  project would not work and I kept getting an error saying "Gradle 3.3
  is required". Using the default Gradle wrapper doesn't work. The only way to fix this was to download Gradle 3.3
  manually and point to the directory in build settings.</p></li>
  <li><p>On running my project, I kept getting a string of errors involving my
  <code>BaseApplication</code> class which extends <code>MultiDexApplication</code>. The
  error goes something like this:</p>
  
  <blockquote>
    <p><code>Error:(19, 62) error: package android.support.multidex does not exist</code></p>
  </blockquote></li>
  </ul>
  
  <p>I am unable to resolve this error. I have <code>buildToolsVersion '25.0.2'</code>, and my project compiled and ran properly before upgrading to Android Studio 2.3. Can anyone help me with this problem?</p>