title: python selenium to click a link
body: <p>since I updated my firefox to 49.02 and selenium to 3.0.1, my previous code to sign in to my <code>bing account</code> does not work.</p>
  
  <p>there is a <code>Sign in</code> link in <code>www.bing.com</code>, I could successfully click this link by calling:</p>
  
  <pre><code>driver.get("http://www.bing.com")
  driver.implicitly_wait(20)
  driver.find_element_by_link_text('Sign in').click()
  </code></pre>
  
  <p>however, after the upgrade, I receive a strange error message which contains no message at all:</p>
  
  <pre><code>selenium.common.exceptions.ElementNotVisibleException: Message:
  </code></pre>
  
  <p>if I only call <code>driver.find_element_by_link_text('Sign in')</code>, I will receive no error message. This seems like selenium could successfully locate this link, but somehow it can not click this button.</p>
  
  <p>I have also tried to locate <code>Sign in</code> by it <code>class name</code> or by clicking the icon instead, but all such efforts are useless.</p>
  
  <p>I do not know if the error is caused by Microsoft to block automated logging in or the error in my code. Helps appreciated!</p>
  
  <p>calling <code>driver.find_element_by_xpath('//a[span = "Sign in"]').click()</code> as suggested by <code>alecxe</code> still does not resolve the issue.</p>