Ruby Error Handling

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How to work around errors caused by axe DevTools Ruby 4.3

Version 4.3.0 and above of the axe DevTools integrations use a new technique when analyzing a page, which opens a new window at the end of a run. Many of the issues outlined in this document address common problems with this technique and their potential solutions.

Having an Out-of-date Driver

A common problem is having an out-of-date driver. To fix this issue make sure that your local installation of geckodriver or chromedriver is up to date.

An example error message for this problem will include a message about switchToWindow. For example:

(node:17566) UnhandledPromiseRejectionWarning: Error: Malformed type for "handle" parameter of command switchToWindow
Expected: string
Actual: undefined

Having Popup blockers enabled

Popup blockers prevent us from opening a new window when analyzing a page. The default configuration for most automation testing libraries should allow popups. Please make sure that you do not explicitly enable popup blockers which may cause an issue while running the tests.


If for some reason you are unable to analyze a page without errors, axe provides a new chainable method that allows you to run the legacy procedure. When using this method axe excludes accessibility issues that may occur in cross-domain frames and iframes.


Axe::Configuration.legacy_mode is deprecated and will be removed in v5.0. Please report any errors you may have while analyzing a page so that they can be fixed before the legacy version is removed.


require "axe/core"

def analyze_page
def open_page

webdriver = open_page
Axe::Configuration.instance.legacy_mode = true
results = analyze_page