https://devzone.nordicsemi.com/f/nordic-q-a/70991/bug-usb-dfu-transport-does-not-work-if-nrf_drv_power_init-was-already-callednRF5 SDK version 17.0.2 In usb_dfu_transport_init we have this: If the nrf_drv_power driver was already initialized, this will return NRF_ERROR_MODULE_ALREADY_INITIALIZED and the transport initialization will fail. app_usbd_init already callsen-USTelligent Community 13Thu, 28 Jan 2021 14:34:50 GMThttps://devzone.nordicsemi.com/thread/291824?ContentTypeID=1Thu, 28 Jan 2021 14:34:50 GMT137ad170-7792-4731-bb38-c0d22fbe4515:0d2c8222-8e23-494f-a41c-1bf8120f0c22Amanda Hsieh<p>Hi,&nbsp;</p> <p>If you refer to the&nbsp;<span>&lt;InstallFolder&gt;\examples\dfu\secure_bootloader\pca10056_usb, you would see it use&nbsp;usb_dfu_transport_init&nbsp;to initial the nrf_drv_power and related drivers. It doesn&#39;t expect that the user initializes the nrf_drv_power driver before it. Or maybe it should check whether the driver is initialized in the&nbsp;usb_dfu_transport_init. Thanks for pointing out that.&nbsp;&nbsp;</span></p> <p>-Amanda H.</p><div style="clear:both;"></div>