I have a Samsung un50ru7100dfxza 4k TV.
I've had a Roku for years and on May 4, in the middle of streaming I suddenly recevied an error that stated HDCP was not supported. I unplugged everything and restarted, which only temporarily solved it. I ordered new HDMI cables that explicilty support HDCP 2.2 and HDMI 2.0 and 4K 60 hz 4:4:4. I still got the error. So I got a new roku, and still receive the error. Even with changing the external device input to input signal plus, the error still occurs. I have used different ports and still get the error. I have changed everything but the TV. It is important to note that I did not have the issue with the TV, old roku, and old cables before May 7.
I've followed all advice online that I can find from both Roku and Samsung. Any new advice would be helpful.
Have you checked for any available updates for the television? Have you tried a factory reset of the television?
Please go to Settings>Support and provide the current software version on the television.