Why do I receive the error 'CONF_DONE pin failed to go high in device X' when I try to JTAG configure my Intel® FPGA using the Intel® Quartus® Prime Software and a download cable?

You may receive this error from the Intel® Quartus® Prime Software if the nCE pin of the device is not connected to GND. For example, in a multi-device passive serial chain where the nCE pin of the first device is connected to GND and the nCEO pin of the first device is feeding the nCE pin of the next device in the chain, the JTAG programming would fail and the Intel® Quartus® Prime Software will report 'CONF_DONE failed to go high in device 2'. This is because the nCE pin of the second device is not connected to GND.

For successful JTAG programming of a device chain, all nCE pins must be connected to GND.