Tips for Fixing HDCP Errors playing iTunes Store HD Video/Movies:
I saw 4 reports of HDCP errors "This movie can be played only on displays that support HDCP (High-bandwidth Digital Content Protection)" when playing back purchased iTunes HD videos/movies after updating to iTunes 11.3.1. They were OK/able to playback iTunes HD content before the update they said, so assuming their display(s) were HDCP compatible. Most noted trying the usual 'zap the pram', reset smc, etc. (Re-detecting displays, disconnecting/reconnecting, verifying cables are OK/swapping cables are other common tips. And remember everything in the chain from source to the display has to be HDCP compliant, including any adapters or switches.)
If you're suddenly seeing HDCP errors with known HDCP compatible hardware and display (not just HD compatible), here are some possible causes, things to check and tips to try:
First, try restarting the Mac and/or cycling power on the Display/TV.
If using Display Mirroring or Airplay, try using only one directly connected display.
Do you have Screen Sharing enabled? If so, disable it (in Apple menu > System Preferences > Sharing) as a test since it's been reported to cause HDCP errors.
(Even if you don't recall ever using it, check to verify it's not enabled.)
Are you using any Screen Capture or Remote Desktop apps/utilities (or startup items) - if so disable/remove them, reboot and test again.
If using any other non-standard/USB Display related addons - remove them as a test. (Test w/o any other display related addons/connections other than a known HDCP monitor)
(Also check for updates to any software/addons after a macOS upgrade/update.)
If none of that applies and you're certain your display is HDCP compatible, try changing the display resolution to a lower setting (i.e. if a 1920x1200 display, try 1920x1080 (1080P), or less as a test). Seems like an odd tip, but some have said this solved the HDCP error problem and afterwards were able to change back to the native/higher resolution without HDCP errors. (Makes me wonder if there was a display prefs issue/corruption previously.)
In some cases nothing may help, and remember that older displays may not be HDCP compatible, including some older Apple Cinema Displays. (I saw some posts that seemed to think that if the display supported HD resolutions, it was also HDCP compliant - but that's not a given. Many older displays have native 1080P or higher resolution but do not support HDCP - aka High-bandwidth Digital Content Protection.)
"About iTunes 11.3.1
iTunes 11.3.1 addresses a problem where subscribed podcasts may stop updating with new episodes and resolves an issue where iTunes may become unresponsive while browsing your podcasts episodes in a list.
File Size: OS X (239.6MB), Windows (112MB), Windows64 (113.5MB)
- OS X version 10.6.8 or later
- 400MB of available disk space
- iTunes in the Cloud, iTunes Match, iTunes Radio availability vary by country
- iTunes Radio requires OS X version 10.7 or later
- iTunes Extras requires OS X version 10.9.3 or later"