Unable to connect to host 127.0.0.1 on port 7055 after 45000 ms. with FF version 26.0 and selenium standalone jar 2.39

Question

I am trying to connect to selenium 2.30 with FF version 26.0 installed in my AWS unix machine but I am getting below error when I start both my client which access selenium.

Also, when I try the same with selenium standalone jar 2.38.0, it works fine but suddenely after some time in a day or two, it starts giving below error with 2.38.0 as well. Not sure why this is happening? Any idea??

project is I have a multithreadin app wherein client keeps executing some threads which pings some URLS and all, it keeps on happening unless some issue like below occurs.

Caused by: org.openqa.selenium.remote.ErrorHandler$UnknownServerException: Unable to connect to host 127.0.0.1     on port 7055 after 45000 ms. Firefox console output:
Error: no display specified
Error: no display specified

Build info: version: 'unknown', revision: 'unknown', time: 'unknown'
System info: os.name: 'Linux', os.arch: 'amd64', os.version: '3.4.76-65.111.amzn1.x86_64', java.version:  '1.7.0_51'
 Driver info: driver.version: FirefoxDriver
    at      org.openqa.selenium.firefox.internal.NewProfileExtensionConnection.start(NewProfileExtensionConnection.java:118)
    at org.openqa.selenium.firefox.FirefoxDriver.startClient(FirefoxDriver.java:250)
    at org.openqa.selenium.remote.RemoteWebDriver.<init>(RemoteWebDriver.java:110)
    at org.openqa.selenium.firefox.FirefoxDriver.<init>(FirefoxDriver.java:197)
    at org.openqa.selenium.firefox.FirefoxDriver.<init>(FirefoxDriver.java:190)
    at org.openqa.selenium.firefox.FirefoxDriver.<init>(FirefoxDriver.java:108)

Answer 1

Update your selenium jars. The new version of firefox(Or different browser) is not supporting old jars of selenium.

Download both Selenium Server (formerly the Selenium RC Server) Selenium Client & WebDriver Language Bindings

Replace them with old jars you are using. Update your Mozilla also so you can get the updated results

source:- http://docs.seleniumhq.org/download/

Answer 2

It looks like you have two different errors going on:

1. Unable to connect to host 127.0.0.1 on port 7055
2. Error: no display specified

The reason for the Unable to connect error is that the version of Selenium Server does not know how to work with the newer version of Firefox. You need to download a newer version of the Selenium Server that supports the newer version of Firefox.

The reason for the Error: no display specified error is that Firefox is being launched, but there is no X server (GUI) running on the remote host. You can use X11 forwarding to run Firefox on the remote host, but display it on your local host. On Mac OS X, you will need to download XQuartz in order to use X11 forwarding.