OTA Failed！Failed to Mcumgr DFU: Invalid header magic number

[spring.liu]

why can cause this  problem！ I'm not familiar with NCS OTA

[spring.liu]

I use NCS 1.5.1  uart example (ncs1.5.1\nrf\samples\bluetooth\peripheral_uart) add the ota, but fail 

  

 Steps are as follows

1. add this code to prj.conf

CONFIG_BOOTLOADER_MCUBOOT=y

CONFIG_MCUMGR=y

CONFIG_MCUMGR_CMD_IMG_MGMT=y

CONFIG_MCUMGR_CMD_OS_MGMT=y

CONFIG_BT_L2CAP_TX_MTU=252

#CONFIG_BT_BUF_ACL_RX_SIZE=256        this in NCS2.0.0 is ok  but ncs1.5.1 without it   so CONFIG_BT_ACL_RX_COUNT replace it

CONFIG_BT_ACL_RX_COUNT=256

CONFIG_MCUMGR_SMP_BT=y

CONFIG_MCUMGR_SMP_BT_AUTHEN=n

CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=2304

2.add this code to main.c

   

• I used this same approach successfully in NCS2.0  。but NCS1.5.1  without CONFIG_BT_BUF_ACL_RX_SIZE and OTA failed。 the reson is MCUmgr disconnecting

[spring.liu]

and how to open the OTA LOG   

CONFIG_BT_DFU_SMP_LOG_LEVEL=4

CONFIG_BT_DEBUG_LOG =y

CONFIG_LOG_DEFAULT_LEVEL=4

this is only