Internal Error: Sub-system: QIS, File: /quartus/synth/qis/qis_primitive_mapper.cpp, Line: 3663 - Internal Error: Sub-system: QIS, File: /quartus/synth/qis/qis_primitive_mapper.cpp, Line: 3663 Description Due to a problem in the Intel® Quartus® Prime Pro Edition software, you may see this internal error when you instantiate any of the following primitives: ALT_INBUF, ALT_OUTBUF, ALT_IOBUF, ALT_BIDIR inside a VHDL 'For Generated' loop. Resolution To work around this problem, unroll the 'For Generate' loop and individually instantiate each of the primitives required as below: 'For Generate' primitives instantiation: inbuf_diff_gen : for j in 0 to 2 generate inbuf_diff_gen : alt_inbuf_diff port map ( i => rx_data_p(j), ibar => rx_data_n(j), o => rx_serial_data(j)); end generate; Individually instantiated primitives: port map ( i => rx_data_p(0), ibar => rx_data_n(0), o => rx_serial_data(0)); inbuf_diff_inst_1 : alt_inbuf_diff port map ( i => rx_data_p(1), ibar => rx_data_n(1), o => rx_serial_data(1)); inbuf_diff_inst_2 : alt_inbuf_diff port map ( i => rx_data_p(2), ibar => rx_data_n(2), o => rx_serial_data(2)); This problem has been fixed beginning with the Intel® Quartus® Prime Pro Edition software version 18.0 Custom Fields values: ['novalue'] Troubleshooting 536523 False ['novalue'] ['FPGA Dev Tools Quartus® Prime Software Pro'] 18.0 17.1.2 ['Programmable Logic Devices'] ['novalue'] ['novalue'] ['novalue']