When HDCP Messes Up

High-bandwidth Digital Content Protection or HDCP is a Digital Rights Management system used in devices with HDMI connections, among others. As with many DRM or "copy protection" schemes it can break and interfere with legitimate use, rather than just work in the background as it should.
For example, if you have an older HDTV set that is not HDCP compliant then you cannot watch any  HDCP compliant content on it. If you plug in your Blu-ray player, a Chromecast, or any other device that follows HDCP standards you’ll either see a blank screen or you’ll see an error message like “ERROR: NON-HDCP OUTPUT” or simply “HDCP ERROR.”
There is an inexpensive solution to this kind of problem - even though it should not be necessary for legitimate users. HowToGeek has the skinny.

It used to be so simple