User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Firefox/68.0

Steps to reproduce:

Connect to a network that has a captive portal, and has a long delay when loading plaintext HTTP resources [this might not be necessary but these are the conditions I can try]

Visit the following URL: https://calvino.polito.it/~fosson/geom16web.pdf (note that cURL reports the certificate as self-signed)

Actual results:

Firefox shows a "Log in to network - You must log in to this network before you can access the Internet". Clicking on "Advanced" shows the page in the screenshot, and clicking "Accept the Risk and Continue" does nothing.

TypeError: doc.body.getAttribute(...) is null - NetErrorChild.jsm:568:30 is logged to the browser console.

Expected results:

Firefox should have showed some "self-signed certificate" warning, and let me override it.

I'm using Nightly 2019-06-11, the UA was erroneously reported as FF68.

Change to Security since the dom element is introduced in bug 1484255
https://searchfox.org/mozilla-central/rev/06bd14ced96f25ff1dbd5352cb985fc0fa12a64e/browser/actors/NetErrorChild.jsm#259

I don't think this should be showing at all, and just the captive portal message...

Actually, I think this was already fixed by bug 1552333 (builds after June 18th), can you confirm?

Indeed, this bug does not appear any more. Thank you.

Thanks!

Bug 1552333 doesn't look like something we'd want to try to backport to earlier releases, calling this wontfix for 68.