Same problem. Started since previous upgrade. I'm running Premiere CC on Mac OSX 10.13.6 on a mid-2011 27" iMac. Today's upgrade has not made any difference. Error still signalled.
LATER: today's upgrade may have sorted it - I hadn't actually performed it on this machine after all! But previous to the upgrade I altered the "Media" preference to remove the hardware rendering option, and that seemed to fix it. After the upgrade I tried with that preference both on and off, and all seems to be OK.
Thanks Carlos for pointing me towards that. I had been looking for the 'Mercury software rendering only' option, which has vanished.