title: Selenium throws error while trying to add extension - "Failed to connect to binary FirefoxBinary" and "Cannot locate node containing extension id"
body: <p>I am trying to get Selenium to install an extension while testing. I am using the latest standalone JAR (<code>selenium-server-standalone-2.26.0.jar</code>) and Firefox 17 to run my tests. The program works perfectly when I am not trying to add the extension.</p>
  
  <p>I have verified multiple times that the extension file that I am trying to use exists and can be accessed by the program and does in fact contain a valid install.rdf because I used it to manually install the extension in my default Firefox profile.</p>
  
  <p>My code is :</p>
  
  <pre><code>FirefoxProfile fp=new FirefoxProfile();
  File ext=new File("myext-2.17.xpi");
          try {
              fp.addExtension(ext);
              fp.setPreference("extensions.myext.version", "myext-2.17");
          } catch (Exception e2) {
              e2.printStackTrace();
          }
  WebDriver wd=new FirefoxDriver(fp);
  </code></pre>
  
  <p>The full Stack Trace is as follows : </p>
  
  <pre><code>Exception in thread "pool-1-thread-2" org.openqa.selenium.WebDriverException: Failed to connect to binary FirefoxBinary(C:\Program Files (x86)\Mozilla Firefox\firefox.exe) on port 7055; process output follows: 
  null
  Build info: version: '2.26.0', revision: '18041', time: '2012-11-01 19:33:38'
  System info: os.name: 'Windows 7', os.arch: 'amd64', os.version: '6.1', java.version: '1.7.0_02'
  Driver info: driver.version: FirefoxDriver
      at org.openqa.selenium.firefox.internal.NewProfileExtensionConnection.start(NewProfileExtensionConnection.java:122)
      at org.openqa.selenium.firefox.FirefoxDriver.startClient(FirefoxDriver.java:243)
      at org.openqa.selenium.remote.RemoteWebDriver.&lt;init&gt;(RemoteWebDriver.java:109)
      at org.openqa.selenium.firefox.FirefoxDriver.&lt;init&gt;(FirefoxDriver.java:189)
      at org.openqa.selenium.firefox.FirefoxDriver.&lt;init&gt;(FirefoxDriver.java:182)
      at org.openqa.selenium.firefox.FirefoxDriver.&lt;init&gt;(FirefoxDriver.java:178)
      at org.openqa.selenium.firefox.FirefoxDriver.&lt;init&gt;(FirefoxDriver.java:95)
      at TrafficGenerator.BrowserWindow.run(BrowserWindow.java:80)
      at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
      at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
      at java.lang.Thread.run(Unknown Source)
  Caused by: org.openqa.selenium.WebDriverException: org.openqa.selenium.WebDriverException: Cannot locate node containing extension id: C:\Users\Vivek\AppData\Local\Temp\unzip3924903411706376479stream\install.rdf
  Build info: version: '2.26.0', revision: '18041', time: '2012-11-01 19:33:38'
  System info: os.name: 'Windows 7', os.arch: 'amd64', os.version: '6.1', java.version: '1.7.0_02'
  Driver info: driver.version: FirefoxDriver
  Build info: version: '2.26.0', revision: '18041', time: '2012-11-01 19:33:38'
  System info: os.name: 'Windows 7', os.arch: 'amd64', os.version: '6.1', java.version: '1.7.0_02'
  Driver info: driver.version: FirefoxDriver
      at org.openqa.selenium.firefox.internal.FileExtension.readIdFromInstallRdf(FileExtension.java:141)
      at org.openqa.selenium.firefox.internal.FileExtension.writeTo(FileExtension.java:60)
      at org.openqa.selenium.firefox.FirefoxProfile.installExtensions(FirefoxProfile.java:465)
      at org.openqa.selenium.firefox.FirefoxProfile.layoutOnDisk(FirefoxProfile.java:443)
      at org.openqa.selenium.firefox.internal.NewProfileExtensionConnection.start(NewProfileExtensionConnection.java:77)
      ... 10 more
  </code></pre>
  
  <p>The error exists on using FF16 and FF9 too.
  Any ideas on what could be the cause of the error and how I could fix it?</p>