[🐛 Bug]: error from remote server causes a secondary error in Ruby library

[jonleighton]

What happened?

An error from a remote Selenium server is not correctly reported when using the selenium-webdriver v4.23.0 library in Ruby.

It appears that a bug in the selenium-webdriver exception handling code causes another exception to be raised.

Note that this problem does not occur in the previous v4.22.0 version.

How can we reproduce the issue?

I can reproduce by deliberately creating a situation where the client cannot obtain a new session within the timeout.

In one terminal, start selenium via a Docker container:

docker run \
  --rm \
  -p "4444:4444" \
  --shm-size="2g" \
  -e SE_SESSION_REQUEST_TIMEOUT=1 \
  -e SE_NODE_MAX_SESSIONS=1 \
  selenium/standalone-chromium:latest

In another terminal, run the following Ruby script:

# test.rb

require "bundler/inline"

gemfile do
  source "https://rubygems.org"
  gem "selenium-webdriver", "4.23.0"
end

2.times.each do
  options = Selenium::WebDriver::Options.chrome
  driver = Selenium::WebDriver.for :remote, url: "http://localhost:4444/wd/hub", options: options
  driver.navigate.to "http://google.com"
end

Relevant log output

/Users/jon/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/selenium-webdriver-4.23.0/lib/selenium/webdriver/remote/response.rb:61:in `set_backtrace': backtrace must be Array of String (TypeError)

          cause.set_backtrace(backtrace)
                              ^^^^^^^^^
	from /Users/jon/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/selenium-webdriver-4.23.0/lib/selenium/webdriver/remote/response.rb:61:in `add_cause'
	from /Users/jon/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/selenium-webdriver-4.23.0/lib/selenium/webdriver/remote/response.rb:41:in `error'
	from /Users/jon/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/selenium-webdriver-4.23.0/lib/selenium/webdriver/remote/response.rb:52:in `assert_ok'
	from /Users/jon/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/selenium-webdriver-4.23.0/lib/selenium/webdriver/remote/response.rb:34:in `initialize'
	from /Users/jon/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/selenium-webdriver-4.23.0/lib/selenium/webdriver/remote/http/common.rb:101:in `new'
	from /Users/jon/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/selenium-webdriver-4.23.0/lib/selenium/webdriver/remote/http/common.rb:101:in `create_response'
	from /Users/jon/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/selenium-webdriver-4.23.0/lib/selenium/webdriver/remote/http/default.rb:103:in `request'
	from /Users/jon/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/selenium-webdriver-4.23.0/lib/selenium/webdriver/remote/http/common.rb:67:in `call'
	from /Users/jon/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/selenium-webdriver-4.23.0/lib/selenium/webdriver/remote/bridge.rb:675:in `execute'
	from /Users/jon/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/selenium-webdriver-4.23.0/lib/selenium/webdriver/remote/bridge.rb:76:in `create_session'
	from /Users/jon/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/selenium-webdriver-4.23.0/lib/selenium/webdriver/common/driver.rb:323:in `block in create_bridge'
	from <internal:kernel>:90:in `tap'
	from /Users/jon/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/selenium-webdriver-4.23.0/lib/selenium/webdriver/common/driver.rb:322:in `create_bridge'
	from /Users/jon/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/selenium-webdriver-4.23.0/lib/selenium/webdriver/common/driver.rb:73:in `initialize'
	from /Users/jon/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/selenium-webdriver-4.23.0/lib/selenium/webdriver/remote/driver.rb:38:in `initialize'
	from /Users/jon/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/selenium-webdriver-4.23.0/lib/selenium/webdriver/common/driver.rb:57:in `new'
	from /Users/jon/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/selenium-webdriver-4.23.0/lib/selenium/webdriver/common/driver.rb:57:in `for'
	from /Users/jon/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/selenium-webdriver-4.23.0/lib/selenium/webdriver.rb:89:in `for'
	from test.rb:10:in `block in <main>'
	from test.rb:8:in `times'
	from test.rb:8:in `each'
	from test.rb:8:in `<main>'

Operating System

macOS Sonoma

Selenium version

Ruby 4.23.0

What are the browser(s) and version(s) where you see this issue?

Chromium 127.0

What are the browser driver(s) and version(s) where you see this issue?

ChromeDriver 127.0.6533.119

Are you using Selenium Grid?

No response

[github-actions]

@jonleighton, thank you for creating this issue. We will troubleshoot it as soon as we can.

---

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Thank you!

[jonleighton]

#14170 probably introduced this problem. CC-ing those involved: @p0deje @ioquatix @aguspe

[aguspe]

Thank you so much @jonleighton for raising this, I will pick this up and investigate later today

[aguspe]

This is my draft PR to fix the issue #14433, I will improve the test later today and put it up for review