ID:21191 Supply voltage value <value> set to the '<name>' power rail is illegal for the selected device.

CAUSE: You attempted to set an illegal supply voltage value to the specified power rail for the selected device. This error can occur if you manually edit the Quartus Prime Settings File (.qsf) to specify the operating conditions of the selected device.

ACTION: Set a valid supply voltage value to the specified power rail. To avoid receiving this message in the future, Intel recommends using the Voltage page of the Settings dialog box to specify the operating conditions of the selected device, rather than manually editing the .qsf.