Error(129015): Output port REGOUTHI on atom "<file name>", which is a twentynm_ddio_in primitive, is not legally connected and/or configured

Description

You might see this error in the Intel® Quartus® Prime Standard Edition Software version 16.1 when you set register mode to DDIO and enable Half Rate Logic in Altera GPIO IP for Intel® Arria® 10 devices. 

Resolution

This problem is fixed starting with the Intel® Quartus® Prime Standard Edition Software version 18.1.