Aside from not needing SafariDriver starting in Safari 10 (or was it 9? I forget) and requiring recent versions of Selenium with older versions of Selenium paired with older Safari using SafariDriver, if you’re like me and haven’t used Selenium/SafariDriver in a while, you might have left the browser with SafariDriver extension.
If you update Mac OS X and Safari, you may still have the extension installed unless you specifically uninstall it.
One interesting quirk about having it installed is that it can now cause problems on certain websites (likely from same core issue from something in the extension’s codebase):
TypeError: Value is not a sequence
This came up for the websites from my company as well as Apple’s iCloud.com.
Once I uninstalled the extension, everything was fine.
autumnator 