title: Displaying an error: “Original error: ‘app’ option is required for reinstall” while start session in Appium
body: <p>I’m new at Appium.
  I defined into ‘<code>Desired Capabilities</code>’ tab needed capabilities such as:</p>
  <ul>
  <li>deviceName</li>
  <li>udid</li>
  <li>platformName</li>
  <li>platformVersion</li>
  <li>appPackage</li>
  <li>appActivity</li>
  </ul>
  <p>After I clicked on the <code>Start Session</code> button, I got the error message <code>“An unknown server-side error occurred while processing the command. Original error: ‘app’ option is required for reinstall”.</code></p>
  <p>Before that, I started a virtual android device but I don't have the right app on my device. Should I connect source code with Appium capabilities and how do I do that? Which tools should be used (Android Studio or IntelliJ IDEA)?</p>