1685893 - Firefox 84.0.1 randomly breaks selenium (python) tests

Status: RESOLVED DUPLICATE of bug 1684827

(Remote Protocol :: Marionette, defect)

Description

[vsopina]

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:82.0) Gecko/20100101 Firefox/82.0

Steps to reproduce:

Once Firefox 84.0.1 was released our automation tests started randomly failing on the following code (simplified):

"
def click_element(element):
old_page = self.driver.find_element_by_tag_name('html')
element.click()
WebDriverWait(self.driver, timeout_sec).until(expected_conditions.staleness_of(old_page))
"

Actual results:

Tests do work on Firefox v.83 and throw random "Timeout exception" on Firefox v.84.

Note: During the debug session it was noticed that geckodriver returns "Webelement reference not seen before" exception in case of failed tests on v.84.

Expected results:

Browser must behave predictably as it used to be with v.83.

Comment 1

[Virginia (please send need info request to Brindusa Tot)]

Hi vsopina,

Thanks for reporting this bug.

I'll add this to the Dom: Core & HTML component in the hope someone from their team can take a look at this and advice.

Regards,
Virginia

Comment 2

[Henrik Skupin [:whimboo][⌚️UTC+2]]

This has been fixed for Firefox 85 via bug 1684827. If it's still happening please attach a trace log to the bug and we can reopen.