Hello, I am trying to use quartus 18.1 version for programming Arria10 device and getting the following error: Error (209066): The instruction register length for the 10AX115S2F45 device at position 1 in the JTAG chain is unknown. - Hello, I am trying to use quartus 18.1 version for programming Arria10 device and getting the following error: Error (209066): The instruction register length for the 10AX115S2F45 device at position 1 in the JTAG chain is unknown. Board type : Dev Board . Adding a scrrenshot of the error msg for referrence Replies: Re: Hello, I am trying to use quartus 18.1 version for programming Arria10 device and getting the following error: Error (209066): The instruction register length for the 10AX115S2F45 device at position 1 in the JTAG chain is unknown. Hi Abe and MShafiq, We updated the Drivers and now the issue has been resolved. Thanks for the help . Replies: Re: Hello, I am trying to use quartus 18.1 version for programming Arria10 device and getting the following error: Error (209066): The instruction register length for the 10AX115S2F45 device at position 1 in the JTAG chain is unknown. Yes I'm agree with Abe. You can try to check the JTAG cable connectivity. Replies: Re: Hello, I am trying to use quartus 18.1 version for programming Arria10 device and getting the following error: Error (209066): The instruction register length for the 10AX115S2F45 device at position 1 in the JTAG chain is unknown. Can you install the standalone Quartus Programmer nd then try. Also check the Jtag cable connectivity.