Error (209053): Unexpected error in JTAG server -- error code 126 - Error (209053): Unexpected error in JTAG server -- error code 126 Description Due to a bug in Quartus® Prime software versions 16.1, 17.0 and 17.1, the programmer may show this error when programming a volatile key into an Arria® V, Cyclone® V or Stratix® V device using a USB-Blaster download cable. This error does not occur when using a USB-Blaster II download cable to program the volatile key. Resolution This problem is fixed beginning with the Intel Quartus Prime software version 18.0. Custom Fields values: ['novalue'] Troubleshooting FB: 498379; False ['novalue'] ['FPGA Dev Tools Quartus® Prime Software Pro'] 18.0 16.1 ['Arria® V FPGAs and SoCs', 'Cyclone® V FPGAs and SoCs', 'Stratix® V FPGAs'] ['novalue'] ['novalue'] ['Download Cable PL-USB-BLASTER-RCN']