If you have stumbled upon this article, you are likely holding onto an ancient piece of iOS history: an iPhone 4S, iPad 2, or iPad 3 running iOS 6.1.x. You have downloaded the legendary tool (often stylized as p0sixspwn or p0sixpwn ), you double-click the executable, and you are met with a frustrating, brick-wall error:

If you cannot downgrade your main PC (e.g., a work laptop), use a Virtual Machine.