Norton "Safe Web" interferes with Firefox
Starting yesterday (March 12), when I tried to open Duolingo in Firefox, I just got a blank page. Duolingo opened fine in Chrome. Today, I did a bit of searching, and found this site https://support.mozilla.org/en-US/questions/1252910#answer-1204613 which suggests that Norton "Safe Web" is interfering with Duolingo. Indeed, when I disabled Safe Web, Duolingo opened up fine.
I haven't had a problem with any other site so far, so I'm wondering if there's something on the Duolingo site that is causing Safe Web to disallow it loading.
Strangely, Norton's "Safe Web Report" for duolingo.com says there are zero threats on the site. https://safeweb.norton.com/report/show_mobile?name=duolingo.com
I started firefox in safe mode, after suspecting addon problems, and lo and behold, duolingo works. After starting in safe mode and shutting firefox down, then opening it again, duolingo works as before. For those not familiar, click the three lines top right in firefox, choose HELP from the dropdown, then "Restart with Add-ons disabled."
I didn't do the "safe mode" thing. I just tried enabling Norton Safe Web again. Now Duolingo is working for me in Firefox, with Norton Safe Mode on, even after I shut down the browser and started it again.
But if the problem starts up again, I'll try the Firefox "safe mode" thing.