Updating Firefox and Selenium solved it for me. I don’t pretend to have an explanation for the root cause however.
- Updated Firefox 48 → 53
- Updated to Selenium 3.4.1
I also reinstalled/updated Geckodriver
using Homebrew
and explicitly used it as an executable for Selenium WebDriver
, but it turned out that it wasn’t necessary to mitigate the “Unable to find matching set of capabilities” error.