SECOND MONITOR HDCP FAILURE & SOLUTIONS
After recently installing a 2nd monitor to serve a music workstation (Kawai SP7 stage piano/midi keyboard, M-Track Quad USB audio and MIDI Interface, and Event 20/20 speakers, plus associated mics etc.) that needed to be physically separate from my iMac, I experienced an HDCP error telling me that the recently installed monitor was incompatible, and suggesting I make sure the iTunes window was entirely within the compatible monitor. It was. In fact the second monitor (which is HDCP compatible) was turned off.
That turned out to be the issue. Apparently the HDCP circuitry/software can tell that there is a DisplayPort cable attached to the Thunderbolt port, but not that the monitor on the other end is turned off. Instead HDCP reads a non-active monitor as non-compatible. My choice is to keep the monitor on, even though its not being used, disconnect the cable, or to completely power down (unplug) the second monitor. Fortunately, the second monitor is on a separate surge protector, so it's simple but kludgey to use it to turn the monitor off (and it saves a small amount of power as well).
Error Specifications:
Date: 24 March 2017.
OS: Sierra 10.12.3 (16D32).
Hardware iMac (Retina 5K, 27-inch, Late 2014),
4 GHz Intel Core i7,
32 GB 1600 MHz DDR3 memory,
1 TB SSD, 12 TB additional disks connected via Thunderbolt,
AMD Radeon R9 M295X 4096 MB,
2nd Bluetooth keyboard and trackpad for music workstation.
2nd Monitor ViewSonic VX2778-SMHD 27" IPS WQHD 1440p,
DisplayPort Cable to iMac Thunderbolt port.
Solutions:
- Leave 2nd monitor running, or
- Disconnect DisplayPort cable from iMac, or
- Turn off the 2nd monitor at power supply.