Due to a problem in the Intel® Quartus® Prime Pro Edition Software version 18.1, you may see this internal error when you compile your project for an Intel Cyclone® 10 device.
This problem occurs when you install the Intel® Quartus® Prime Pro Edition Software with only the Intel® Cyclone® 10 device support.
To work around this problem, install the Intel® Arria® 10 device support pack.
This problem is scheduled to be fixed in a future version of the Intel® Quartus® Prime Pro Edition Software.