Error (13657): VHDL expression error at <file name>.vhd: expression has 1 element, but must have 2 elements - Error (13657): VHDL expression error at <file name>.vhd: expression has 1 element, but must have 2 elements Description Due to a problem in the Quartus® Prime Pro Edition software version 17.1 and earlier, you may see this error when using a reduction operator (for example, OR_REDUCE) on a single-element array. In VHDL 2008, this should return the value of the element. Resolution To work around this problem, do not use reduction operators on single-element arrays. This problem will be fixed in a future release of the Quartus® Prime Pro Edition software. Custom Fields values: ['novalue'] Troubleshooting FB: 531544; False ['novalue'] ['FPGA Dev Tools Quartus® Prime Software Pro'] 18.1 17.1 ['Programmable Logic Devices'] ['novalue'] ['novalue'] ['novalue']