title: UnknownError: null protractor
body: <p>I am following <a href="https://angular.github.io/protractor/#/tutorial" rel="nofollow noreferrer">this tutorial</a></p>
  
  <p>I followed steps except according <a href="https://stackoverflow.com/a/30499817/492258">this post</a><br>
  instead of </p>
  
  <pre><code>npm install -g protractor
  </code></pre>
  
  <p>I applied </p>
  
  <pre><code>npm install -g protractor --no-optional
  </code></pre>
  
  <p>I successfully completed <a href="https://angular.github.io/protractor/#/tutorial#step-0-write-a-test" rel="nofollow noreferrer">Step 0 - write a test</a></p>
  
  <pre><code>expect(browser.getTitle()).toEqual('Super Calculator');
  </code></pre>
  
  <p>However when I try  <a href="https://angular.github.io/protractor/#/tutorial#step-1-interacting-with-elements" rel="nofollow noreferrer">Step 1 - interacting with elements</a> </p>
  
  <pre><code>element(by.model('first')).sendKeys(1);
  </code></pre>
  
  <p>it gives error:</p>
  
  <pre><code>Using the selenium server at http://localhost:4444/wd/hub
  [launcher] Running 1 instances of WebDriver
  F
  
  Failures:
  
    1) Protractor Demo App should add one and two
     Message:
       UnknownError: null
     Stacktrace:
       UnknownError: null
     //... continue stack trace
  </code></pre>
  
  <p>I can see that I can access dom element by testing:</p>
  
  <pre><code>element(by.model('firstXXX')).sendKeys(1);
  </code></pre>
  
  <p>then it says, </p>
  
  <pre><code>NoSuchElementError: No element found using locator: by.model("firstXXX")
  </code></pre>
  
  <p>What could be reason for error message mentioned above:</p>
  
  <pre><code>Message:
       UnknownError: null
  </code></pre>
  
  <p>Also output from <code>webdriver-manager start</code> console:</p>
  
  <pre><code>16:41:27.526 INFO - Executing: [send keys: null null, [1]])
  16:41:27.527 WARN - Exception thrown
  java.lang.NullPointerException
          at org.openqa.selenium.remote.server.handler.SendKeys.call(SendKeys.java:49)
          at org.openqa.selenium.remote.server.handler.SendKeys.call(SendKeys.java:1)
          at java.util.concurrent.FutureTask.run(Unknown Source)
          at org.openqa.selenium.remote.server.DefaultSession$1.run(DefaultSession.java:168)
          at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
          at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
          at java.lang.Thread.run(Unknown Source)
  16:41:27.530 WARN - Exception: null
  16:41:27.658 INFO - Executing: [delete session: 157e0397-52e0-4d03-b8ee-aef453cd83a2])
  16:41:28.843 INFO - Done: [delete session: 157e0397-52e0-4d03-b8ee-aef453cd83a2]
  </code></pre>