Problems accessing or browsing HTTPS websites using Opera 12.11+

If you've ever noticed having difficulties using HTTPS websites using Opera 12.11 or up, here's how to fix it. This problem may manifest itself with a minor error or may even block you completely from using a website. You may notice these problems may occur every time or it may be spotty. Here's how I fixed the problem.

Problem: You cannot use HTTPS websites.

Impact: You cannot access email, online shops, etc which all use HTTPS for security.

Solution:
In the address bar of your Opera browser, type opera:config and hit enter. This opens Opera's preference configuration page.

At the top of your Preferences Editor page, type spdy in the quick find search bar.

All configurations for options with "spdy" in their names will show up. We're interested in those in the Network section. If it is not already expanded, expand it and go to the bottom of the section.

Here's the important part: uncheck the boxes labelled "Use Spdy2" and "Use Spdy3" like in the image below. Click the "Save" button to make your changes and you're good to go.