https://devzone.nordicsemi.com/f/nordic-q-a/2663/nrf51822-bootloader-download-problem-with-nrfgo-studioHi All. I am trying to download the Bootloader to nRF51822 Dev Kit using nRFgo Studio (32 bit, v 1.15.1.2691) but getting an Error. &quot;ERROR: Attempted to write to UICR page while programming application&quot; Before download the &quot;bootloader.hex&quot;, Ien-USTelligent Community 13Mon, 02 Jun 2014 12:18:56 GMThttps://devzone.nordicsemi.com/thread/10469?ContentTypeID=1Mon, 02 Jun 2014 12:18:56 GMT137ad170-7792-4731-bb38-c0d22fbe4515:db8da9b3-43b3-4878-bf34-6dcdc58ef125John<p>If I recall correctly, the nRFgostudio cannot write the UICR register and the bootloader programming needs to modify UICR. You can program it using the command line tool nrfjprog. I program mine with the following command &quot;nrfjprog --program bootloader.hex --reset&quot;. If you search the forum, there are several rather good articles that go into more detail on this.</p><div style="clear:both;"></div>