It’s a cable standard that’s put into place to prevent piracy.
It can, however, interrupt signals even in otherwise innocuous situations.
However, if your goal is to watch content, alternative sourcing methods might work, too.
The devices and cables must be HDCP compliant.
If the problem relates to a major investmentlike an old TVthen your costs correspondingly increase.
Insert an HDMI splitter.
A splitter that ignores HDCP requests creates a pathway that’s immune to this error.
Position the splitter between the output and input rig.
Use an alternative setup.
In other words, if one rig or cable isn’t HDCP compliant, you get an HDCP error.