I take bootloader_secure_ble example for pca10056 build it and use hex file to program using nRFGo Studio get error verification Failed. if i programmed with keil then load successfully and work as expected even i used
SDK\nRF5_SDK_13.0.0_04a0bfd\examples\dfu\bootloader_secure_ble\pca10056_debug\hex\secure_dfu_ble_s140_pca10056_debug.hex
then also got same error Verification Failed.png