Serial bootloader Verification failure

Hi

I am trying to use the serial bootloader to upgrade nrf52 application, but I get verification failure.

I am using nrf52832 with SDK 13.0.0 & S132 SoftDevice v4.0.2. I have loaded experimental_bootloader_secure_serial project to the device and I am trying to upload dfu_test_app_hrm_s132.zip test image.

I am using nrfUtil version 3.4.0 to send the following command: nrfutil dfu serial -pkg dfu_test_app_hrm_s132.zip -p COM3 -b 38400 -fc 0

this is the log I see in Jlink RTT viewer:

:INFO:Inside main
:DEBUG:In nrf_bootloader_init
:DEBUG:In real nrf_dfu_init
:DEBUG:running nrf_dfu_settings_init
:DEBUG:Enter nrf_dfu_continue
:ERROR:Single: Invalid bank
:DEBUG:Application sent bootloader request
:DEBUG:In nrf_dfu_transports_init
:DEBUG:num transports: 1
:DEBUG:UART initialized
:DEBUG:After nrf_dfu_transports_init
:DEBUG:Waiting for events
:WARNING:Received unsupported OP code
:DEBUG:Sending Response: [0x9, 0x3]
:DEBUG:Set receipt notif
:DEBUG:Sending Response: [0x2, 0x1]
:DEBUG:Received get serial mtu
:DEBUG:Sending Response: [0x7, 0x1]
:DEBUG:Received select object
:INFO:Valid Command: NRF_DFU_OBJECT_OP_SELECT
:DEBUG:Sending Response: [0x6, 0x1]
:DEBUG:Received create object
:INFO:Before OP create command
:INFO:Valid Command Create
:DEBUG:Sending Response: [0x1, 0x1]
:INFO:Before OP write command
:INFO:Before OP write command
:DEBUG:Received calculate CRC
:INFO:Valid Command CRC
:DEBUG:Sending Response: [0x3, 0x1]
:DEBUG:Received execute object
:INFO:Before OP execute command
:INFO:Valid command execute
:INFO:
:INFO:PB: Init packet data len: 61
:INFO:Handling signed command
:INFO:Calculating init packet hash
:INFO:Verify signature
:ERROR:Signature failed
:ERROR:Prevalidate failed!
:DEBUG:Sending Response: [0x4, 0x5]

Please advise

Regards Yaron