https://devzone.nordicsemi.com/f/nordic-q-a/19072/sdk13-softdevice-s132-5-0-can-not-use-dfuHi, Nordic I check SDK13.0 bootloader_secure sample, it do not work nrfjprog download bootloader_secure use nRF Connect app in Android mobile phone to DFU (ble_dfu_send_hex\test_images_update_nrf52832*.zip) it can not starten-USTelligent Community 13Thu, 19 Jan 2017 00:54:53 GMThttps://devzone.nordicsemi.com/thread/73760?ContentTypeID=1Thu, 19 Jan 2017 00:54:53 GMT137ad170-7792-4731-bb38-c0d22fbe4515:21da2ec5-f418-4b80-88ca-70c088a7c752Chaw<p>Thanks. I will try.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/73759?ContentTypeID=1Wed, 18 Jan 2017 11:57:54 GMT137ad170-7792-4731-bb38-c0d22fbe4515:10170732-6f92-4f7a-9fc0-6e88694eb188bjorn-spockeli<p>Prevalidate failed means that the bootloader has rejected the image. If you have replaced the debug public key in the bootloader, then you cannot use the test images provided in the SDK. You have to create a new firmware image with nrfutil that is signed with the private key that you used to create the public key. THis is done with the following command:</p> <pre><code>nrfutil pkg generate --hw-version 52 --sd-req 0x90 --application-version 2 --application &lt;name of application hex&gt;.hex --key-file &lt;name of key file&gt;.pem &lt;name of the zip file to be generated&gt;.zip </code></pre><div style="clear:both;"></div>