DFU request 4 failed with error: 0xB

Question

Hi,
I am new with nRF microcontrollers.
I created a custom board that mounts the nRF52840 microcontroller. I made a firmware that uses BLE to exchange data and everything works fine.
Now I want to use the OTA DFU.
I used the example provided in the SDK: (examples \ dfu \ secure_bootloader \ pca10056_s140_ble_debug).

I created a Distribution packet (ZIP) with the command: python nordicsemi/__main__.py pkg generate --application hand.hex hand.zip --hw-version 1 --sd-req 0x100 --application-version 1 --key-file priv.pem
When I connect to the DfuTarg device and select the zip file to send, the device disconnects. The error "<warning> nrf_dfu_ble: DFU request 4 failed with error: 0xB" appears on the Debug Terminal.
Can anyone help me understand why the operation is not successful?
I use SoftDevice s140 (7.2.0).
Below is the contents of the Debug Terminal:

<info> app: Inside main
<debug> app: In nrf_bootloader_init
<debug> nrf_dfu_settings: Calling nrf_dfu_settings_init()...
<debug> nrf_dfu_flash: Initializing nrf_fstorage_nvmc backend.
<debug> nrf_dfu_settings: Using settings page.
<debug> nrf_dfu_settings: Copying forbidden parts from backup page.
<debug> nrf_dfu_settings: Destination settings are identical to source, write not needed. Skipping.
<info> nrf_dfu_settings: Backing up settings page to address 0xFE000.
<debug> nrf_dfu_settings: Destination settings are identical to source, write not needed. Skipping.
<debug> app: Enter nrf_bootloader_fw_activate
<info> app: No firmware to activate.
<info> app: Boot validation failed. No valid app to boot.
<debug> app: DFU mode because app is not valid.
<info> nrf_bootloader_wdt: WDT is not enabled
<debug> app: in weak nrf_dfu_init_user
<debug> app: timer_stop (0x20005994)
<debug> app: timer_activate (0x20005994)
<info> app: Entering DFU mode.
<debug> app: Initializing transports (found: 1)
<debug> nrf_dfu_ble: Initializing BLE DFU transport
<debug> nrf_dfu_ble: Setting up vector table: 0x000F1000
<debug> nrf_dfu_ble: Enabling SoftDevice.
<debug> nrf_dfu_ble: Configuring BLE stack.
<debug> nrf_dfu_ble: Enabling the BLE stack.
<debug> nrf_dfu_ble: No advertising name found
<debug> nrf_dfu_ble: Using default advertising name
<debug> nrf_dfu_ble: Advertising...
<debug> nrf_dfu_ble: BLE DFU transport initialized.
<debug> nrf_dfu_flash: Initializing nrf_fstorage_sd backend.
<debug> app: Enter main loop
<debug> nrf_dfu_ble: Connected
<debug> nrf_dfu_ble: Received BLE_GAP_EVT_DATA_LENGTH_UPDATE_REQUEST.
<debug> nrf_dfu_ble: Received BLE_GAP_EVT_DATA_LENGTH_UPDATE (27, max_rx_time 328).
<debug> nrf_dfu_ble: Received BLE_GAP_EVT_CONN_PARAM_UPDATE
<debug> nrf_dfu_ble: max_conn_interval: 12
<debug> nrf_dfu_ble: min_conn_interval: 12
<debug> nrf_dfu_ble: slave_latency: 0
<debug> nrf_dfu_ble: conn_sup_timeout: 600
<debug> nrf_dfu_ble: Received BLE_GAP_EVT_CONN_PARAM_UPDATE
<debug> nrf_dfu_ble: max_conn_interval: 6
<debug> nrf_dfu_ble: min_conn_interval: 6
<debug> nrf_dfu_ble: slave_latency: 0
<debug> nrf_dfu_ble: conn_sup_timeout: 500
<debug> nrf_dfu_ble: Received BLE_GAP_EVT_CONN_PARAM_UPDATE
<debug> nrf_dfu_ble: max_conn_interval: 12
<debug> nrf_dfu_ble: min_conn_interval: 12
<debug> nrf_dfu_ble: slave_latency: 0
<debug> nrf_dfu_ble: conn_sup_timeout: 600
<debug> nrf_dfu_ble: Received BLE_GATTS_EVT_EXCHANGE_MTU_REQUEST (request: 517, reply: 247).
<debug> nrf_dfu_ble: Received BLE_GAP_EVT_DATA_LENGTH_UPDATE_REQUEST.
<debug> nrf_dfu_ble: Received BLE_GAP_EVT_DATA_LENGTH_UPDATE (251, max_rx_time 2120).
<debug> nrf_dfu_req_handler: Handle NRF_DFU_OP_OBJECT_SELECT (command)
<debug> nrf_dfu_req_handler: Request handling complete. Result: 0x1
<debug> nrf_dfu_ble: Set receipt notif
<debug> nrf_dfu_req_handler: Handle NRF_DFU_OP_RECEIPT_NOTIF_SET
<debug> nrf_dfu_req_handler: Request handling complete. Result: 0x1
<debug> app: Shutting down transports (found: 1)
<debug> nrf_dfu_req_handler: Handle NRF_DFU_OP_OBJECT_CREATE (command)
<debug> app: timer_stop (0x20005994)
<debug> app: timer_activate (0x20005994)
<debug> nrf_dfu_req_handler: Request handling complete. Result: 0x1
<debug> nrf_dfu_ble: Buffer 0x200092C8 acquired, len 141 (244)
<debug> nrf_dfu_req_handler: Handle NRF_DFU_OP_OBJECT_WRITE (command)
<debug> nrf_dfu_ble: Freeing buffer 0x200092C8
<debug> nrf_dfu_req_handler: Request handling complete. Result: 0x1
<debug> nrf_dfu_req_handler: Handle NRF_DFU_OP_CRC_GET (command)
<debug> nrf_dfu_req_handler: Request handling complete. Result: 0x1
<debug> nrf_dfu_req_handler: Handle NRF_DFU_OP_OBJECT_EXECUTE (command)
<debug> nrf_dfu_validation: PB: Init packet data len: 64
<info> nrf_dfu_validation: Signature required. Checking signature.
<info> nrf_dfu_validation: Calculating hash (len: 64)
<info> nrf_dfu_validation: Verify signature
<info> nrf_dfu_validation: Image verified
<warning> nrf_dfu_ver_validation: Faulty HW version.
<warning> nrf_dfu_validation: Prevalidation failed.
<debug> nrf_dfu_validation: Init command:
<debug> nrf_dfu_validation: 08 01 10 01 1A 02 80 02|........
<debug> nrf_dfu_validation: 20 00 28 00 30 00 38 BC| .(.0.8.
<debug> nrf_dfu_validation: BB 0D 42 24 08 03 12 20|..B$...
<debug> nrf_dfu_validation: A9 CD B1 8F 69 AD 38 79|....i.8y
<debug> nrf_dfu_validation: 2E 77 F7 2F 2D 07 60 17|.w./-.`.
<debug> nrf_dfu_validation: 0C 29 18 AB 36 79 AE 7E|.)..6y.~
<debug> nrf_dfu_validation: 6D E4 70 DF A5 89 04 97|m.p.....
<debug> nrf_dfu_validation: 48 00 52 04 08 01 12 00|H.R.....
<debug> nrf_dfu_req_handler: Request handling complete. Result: 0xB
<warning> nrf_dfu_ble: DFU request 4 failed with error: 0xB
<debug> nrf_dfu_ble: Received BLE_GAP_EVT_CONN_PARAM_UPDATE
<debug> nrf_dfu_ble: max_conn_interval: 6
<debug> nrf_dfu_ble: min_conn_interval: 6
<debug> nrf_dfu_ble: slave_latency: 0
<debug> nrf_dfu_ble: conn_sup_timeout: 500
<debug> nrf_dfu_ble: Received BLE_GAP_EVT_CONN_PARAM_UPDATE
<debug> nrf_dfu_ble: max_conn_interval: 12
<debug> nrf_dfu_ble: min_conn_interval: 12
<debug> nrf_dfu_ble: slave_latency: 0
<debug> nrf_dfu_ble: conn_sup_timeout: 600