So there's the semiconductor vendor's website, which contains a PDF datasheet I need to see....
Its SSL certificate expired yesterday. No big deal, right? I can tell the browser to ignore the error and connect anyway, or just use regular HTTP?
Nope. The site's configured for something called HSTS, which apparently means that browsers are forbidden to connect insecurely. Just in case, you know, someone's spoofing the site to distribute altered datasheets.
Maybe if I tried using an outdated browser? Or perhaps some other site has a cached datasheet. Or I could design in some other vendor's part.