Error(19173): The instance name "altshift_taps:datwords_rr_rtl_0" is already in use elsewhere in this scope. If instantiated in a generate block, ensure the block is named. - Error(19173): The instance name "altshift_taps:datwords_rr_rtl_0" is already in use elsewhere in this scope. If instantiated in a generate block, ensure the block is named. Description Due to a problem in the Intel® Quartus® Prime Pro Edition Software version 18.0 Update 1 and earlier, you may see this synthesis error message during compilation when a 50G Interlaken Intel® FPGA IP is instantiated in an Intel® Arria® 10 design. Resolution To work around this problem, add the following in the Quartus Setting File ( .qsf ) to prevent the affected register being inferred as altshift_taps . For example: set_instance_assignment -name AUTO_SHIFT_REGISTER_RECOGNITION OFF -to * -entity ilk_iw4_rx_channel_filter This problem is fixed starting in the Intel® Quartus® Prime Pro Edition Software version 18.1. Custom Fields values: ['novalue'] Troubleshooting FB: 583608; True ['Interlaken - 50G for 28nm and 20nm devices (PRIMARY) IP-ILKN/50G'] ['FPGA Dev Tools Quartus® Prime Software Pro'] 18.1 18.0.1 ['Arria® 10 FPGAs and SoCs'] ['novalue'] ['novalue'] ['novalue']