Problems running WebDriver on Firefox 26?

The Issue

I had a quick look at version 26 of Firefox today, because a fair few people contacted me, saying they had been having issues with it.

Based on forums and calls for help, these people weren’t the only ones.

But, not everyone is experiencing the problem, so there is something odd going on.

I could experience the problem on my main Windows 8 machine, but I hadn’t noticed, because I hadn’t upgraded to version 26 of Firefox.

First the Workaround

The fix I used was to downgrade my version of firefox to 25.0.1

And WebDriver worked fine for my basic test, I tried WebDriver versions 2.38.0 up to version 2.40.0.

I installed Firefox version 27.0b2, and it failed with the same problem I experienced with version 26.

I don’t know the root of the problem I’m experiencing, but my workaround will be to stick on Firefox 25 for my automation work.

Remember to use the Firefox Options \ Upgrade, and set it to not upgrade.

The Salutary Lesson

This might seem extreme, but when doing automation, we need to control the versions of software we test with. If you allow your browser to automatically update without your knowledge then you don’t know if your automation fails because of something you did, or something environmental.

Control of your environment means that when a problem happens, it is most likely something you did.

Given that other people have managed to get WebDriver working with Firefox 26. It might be an operating system based issue, or a plugin issue, or a heaven-knows-what issue.


When faced with problems like these:

  1. Check if anyone else is having the problem
  2. Did anyone find a solution? Try it.
  3. Find a workaround. (First try downgrading to a known working state)
  4. Investigate roll forward options

If execution against version 26 is important to you, try running Firefox on a VM with a different operating system, perhaps from Or try running against Saucelabs.

But DO. DO keep control of your execution environments and the software versions running on them.

This entry was posted in Firefox, Selenium Simplified Blog, WebDriver. Bookmark the permalink.

16 Responses to Problems running WebDriver on Firefox 26?

  1. Pingback: Testing Bits – 12/22/13-12/28/13 | Testing Curator Blog

  2. Normandie says:

    Problem as fixed on Dec 21, 2013.

    • Alan says:

      Unfortunately I tried it and wrote this post on December 26th. As the post says, some people are having problems, some are not.

  3. Ark says:

    Nice post. I was having this problem as well. Downgrading to version 25 and disabling automatic updates has seemed to stabilize the environment for the time being.

    My guess is that it’s a plug-in issue, but I’m not entirely too sure.

    • Alan says:

      Thanks Ark, I haven’t had time to fully investigate the cause, I just downgraded too in order to keep the tests running.

  4. Bhargav says:


    I am trying to run the below code for webdriver but i am getting Exception in thread “main” java.lang.NoClassDefFoundError.Can you please help me?

    import org.openqa.selenium.WebDriver;
    import org.openqa.selenium.firefox.FirefoxDriver;

    public class SeleniumDemo {

    public static void main(String[] args)

    WebDriver driver=new FirefoxDriver();


    I am using selenium server 2.39.0 and firefox 26.Can you please tell what is the issue? I am unable to run any tests.


  5. Sujendra says:

    I too had the same problem. I noticed that webdriver browser strangely had skype logo on its status bar. I removed the Skype click to call addin and now its working fine for me. Make sure that when you have this kind of problem no addons are being loaded into your web driver browser. Hope this helps. 🙂

  6. Bhargav says:

    Hi Alan,

    I tried with FF 27 and also IE 9.But still i am facing the same issue.Can you suggest any workaround or the cause for this issue?


    • Alan says:

      The way I finally got this running on my main machine was to go into my .m2 repository folder and delete the org.seleniumh1.selenium folders, then do a mvn clean to have maven re-download selenium and the firefox driver.

  7. tester says:

    i’ve made my code more robust and it’s perfectly fine in latest chrome version and IE with selenium 2.39 (java). Only firefox the script hang, not performing button click. sure tht nothing wrong with my code. hope selenium release new version (2.40) asap. tried ff version 22 till the latest, same result though, test hang not doing click.

  8. Gunnar says:

    I seem to have another but yet problem with 2.40.0 and firefox older than 27/28.
    When the tests add text to some field before clicking some button, random characters are added sometimes. It happens without any common pattern and very intermittently.
    For instance one test searching for a number 440032215144 can end up with 440^0322~~15144 which of course will end with a failing test. Very annoying and unfortunately the trick by cleaning the selenium repository does not help. A forced upgrade to FF 28 solves it but it is really bad if the driver is not backward comptaible.

  9. Sweta says:

    Thanks for the post! I am having problems running selenium 2.41 on the latest chrome browser. I tried downgrading it, but cannot find any chrome old versions online. Any idea?

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