Exception: Failed to start new browser session: Error while launching browser Selenium in Python

Question

I am getting the following errors when running a basic Selenium test script in Python:

======================================================================
ERROR: test_untitled (__main__.TestTesting)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "TestTesting.py", line 15, in setUp
    self.selenium.start()
  File "/usr/lib/python2.6/dist-packages/selenium.py", line 166, in start
    result = self.get_string("getNewBrowserSession", [self.browserStartCommand, self.browserURL])
  File "/usr/lib/python2.6/dist-packages/selenium.py", line 195, in get_string
    result = self.do_command(verb, args)
  File "/usr/lib/python2.6/dist-packages/selenium.py", line 191, in do_command
    raise Exception, data
Exception: Failed to start new browser session: Error while launching browser

----------------------------------------------------------------------
Ran 1 test in 20.427s

FAILED (errors=1)

The code was generated from the Selenium IDE, the firefox plug in, so I am not sure why it doesn't work. My guess is some sort of configuration is incorrect, but I am not sure. Here is my code:

from selenium import selenium

class TestTesting(unittest.TestCase):
    def setUp(self):
        self.verificationErrors = []
        self.selenium = selenium("localhost", 4444, "*firefox", "http://www.google.com/")
        self.selenium.start()

    def test_untitled(self):
        sel = self.selenium
        sel.open("/firefox?client=firefox-a&rls=org.mozilla:en-US:official")
        sel.type("sf", "test")
        sel.click("btnG")
        sel.wait_for_page_to_load("30000")

    def tearDown(self):
        self.selenium.stop()
        self.assertEqual([], self.verificationErrors)

if __name__ == "__main__":
    unittest.main()

The server is running on Ubuntu.

How can I avoid this error?

Answer 1

The fix that I got to work was that the display for firefox was not set. So I needed to execute the following statement:

export DISPLAY=:0

right before I started the Selenium server. This solve the issue, but a new one has arisen.

Answer 2

This normally happens when another firefox is already opened. i.e. You are using specific FF profile to tet application. When you run the script, close FF.