undefined method `delete' for nil:NilClass (NoMethodError) capybara, selenium-webdriver and firefox in arch linux - selenium-webdriver

Question

I am writing because I am having troubles running a test using cucumber and capybara. I am using capybara framework with selenium-driver. This is my env.rb
require 'capybara/cucumber'
Capybara.default_driver = :selenium
This is my steps.rb file
Given (/^I am on Youtube$/) do
visit "http://www.youtube.com"
end
When (/^I fill in "([^"]*)" with "([^"]*)"$/) do |field, value|
fill_in(field, :with => value)
end
When (/^I press "([^"]*)"$/) do |button|
click_button(button)
end
Then (/^I should see "([^"]*)"$/) do |text|
page.should have_content(text)
end
And this the output that i obtain. I tried to execute the same file with cucumber in a Mac system and it works. I am using Arch Linux (antergos) with kernel version 4.10.6-1-ARCH #1 SMP PREEMPT
Feature: YouTube has a search function.
Scenario: Search for a term # features/youtube_search.feature:3
Given I am on Youtube # features/step_definitions/youtube_search_steps.rb:1
undefined method `delete' for nil:NilClass (NoMethodError)
./features/step_definitions/youtube_search_steps.rb:2:in `/^I am on Youtube$/'
features/youtube_search.feature:4:in `Given I am on Youtube'
When I fill in "search_query" with "text adventure" # features/step_definitions/youtube_search_steps.rb:5
And I press "search-btn" # features/step_definitions/youtube_search_steps.rb:9
Then I should see "GET LAMP: The Text Adventure Documentary" # features/step_definitions/youtube_search_steps.rb:13
Failing Scenarios:
cucumber features/youtube_search.feature:3 # Scenario: Search for a term
1 scenario (1 failed)
4 steps (1 failed, 3 skipped)
0m1.898s
NOTE: When I run the cucumber command, a new firefox window is opened, but I see the error mentioned in the terminal and test not continue.
Thank you all in advance.

Answer 1

I had this problem. It happens when the selenium-webdriver and Firefox versions don't match. As Firefox gets updated fairly often you will get this error from time to time. If you update your selenium-web it should fix the problem. It did for me.