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Firefox Not Connected Exception in Selenium

Firefox Not Connected Exception in Selenium

If your Selenium scripts that were working previously — have suddenly stopped functioning, the culprit might be the latest Firefox browser update.

Many users encounter this issue when Firefox updates to a newer version. This typically happens because the updated browser version is no longer compatible with the existing Selenium WebDriver JAR files. As a result, scripts may fail to execute properly.

First Steps to Troubleshoot

  1. Check for Selenium Updates
    Visit the official Selenium website to download the latest Selenium WebDriver version. Always ensure that you’re using the most recent compatible version.

  2. Rollback Firefox (if necessary)
    If you’re already using the latest Selenium version and still facing issues, you may need to downgrade Firefox to a previous version until Selenium releases an update that supports the latest Firefox version.

 

Common Error Message

A frequent issue users report is that the WebDriver launches the Firefox browser but does nothing beyond opening the window.

The following error is displayed :

org.openqa.selenium.firefox.NotConnectedException:
Unable to connect to host 127.0.0.1 on port 7055 after 45000 ms.

Solutions

Fixes for the problem are shown as follows:

  • Ensure you are using the Latest Selenium Server JAR in your project’s library.

  • Replace any existing Selenium JAR files in your project with updated versions to avoid version mismatch errors.

  • Review the Selenium Change Log for compatibility notes and updates.

Important Compatibility Fix

Selenium WebDriver version 2.53.1 was released on June 30, 2016, and is confirmed to work with Firefox 47.0.1.
You can download it here: Download selenium-server-standalone-2.53.1.jar