Today I Learned

Selenium::WebDriver::Error::NoSuchDriverError

We’ve recently experienced some peculiar errors when processing capybara-based automation scripts on Heroku. Most of the time, the error returned did not show anything useful…

Selenium::WebDriver::Error::NoSuchDriverError: no such session

yet for a brief period of time, following error was reported when attempting to access capybara session

Selenium::WebDriver::Error::UnknownError: unknown error: session deleted because of page crash
from tab crashed

Finally, after spotting this comment we’ve reduced chrome window size from 1920,1200 to 1440,900 and the problem is no longer present.

The root reason is unknown, but most likely it is at least partially related to running out of memory (reference). Most of recommendations when using docker in this scenario, was to increase shm-size, by providing --shm-size=2g to docker run. That was not an option for us though…

Hope it helps in case you run into similar situation.