It’s a new year, and with it comes new resolve to keep current with modern web development technologies! I had begun working through the recently-added PHP Path on Code School, and almost immediately I ran into a problem wherein the submit button on a quiz page caused the page to quit working.
I reloaded the page and opened Chrome DevTools with F12 to see if any errors could be seen there. Sure enough, a couple of Mixed Content errors appeared when I tried to submit an answer again:
I figured at first that there must be something wrong on the Code School web server. Because, of course the problem’s not on our side, right?! It then occurred to me that I run the HTTPS Everywhere extension (which I highly recommend, by the way) in Chrome. I decided to turn it off while using the Code School site to see if that would resolve the issue.
That fixed the problem! The moral of this story is that while problems with HTTPS certs or web server settings could cause this error, check first to see if HTTPS Everywhere is the source of your troubles.
Nota bene: This fix could apply not only to Chrome, but to any browser that can run this extension.