Download client stops when segger RTT log is enabled and debugger connection removed

Hi,

My device : nrf1960 DK

nrf SDK : v1.9.1

prj.conf

CONFIG_TRUSTED_EXECUTION_NONSECURE=y


# General config
CONFIG_REBOOT=y
CONFIG_RING_BUFFER=y

# LOGGNG
CONFIG_LOG=y
CONFIG_LOG_BUFFER_SIZE=2048
CONFIG_LOG2_MODE_DEFERRED=y
CONFIG_CBPRINTF_FP_SUPPORT=y
CONFIG_LOG_DEFAULT_LEVEL=4

# Console
CONFIG_PRINTK=y
CONFIG_UART_CONSOLE=n
CONFIG_SHELL=y
CONFIG_KERNEL_SHELL=y
CONFIG_DEVICE_SHELL=y
CONFIG_POSIX_CLOCK=y
CONFIG_DATE_SHELL=y
CONFIG_SHELL_STACK_SIZE=1536
CONFIG_SHELL_BACKEND_SERIAL=n
CONFIG_SHELL_LOG_BACKEND=y
CONFIG_SHELL_RTT_LOG_LEVEL_DBG=y
CONFIG_SHELL_RTT_INIT_LOG_LEVEL_WRN=y

CONFIG_THREAD_MONITOR=y
CONFIG_INIT_STACKS=y
CONFIG_BOOT_BANNER=n
CONFIG_THREAD_NAME=y

#enable RTT shell
CONFIG_USE_SEGGER_RTT=y
CONFIG_SHELL_BACKEND_RTT=y
CONFIG_SEGGER_RTT_BUFFER_SIZE_DOWN=32

# UART
CONFIG_UART_ASYNC_API=y

# Modem library
CONFIG_NRF_MODEM_LIB=y
CONFIG_MODEM_INFO=y

CONFIG_MODEM_KEY_MGMT=y
CONFIG_DOWNLOAD_CLIENT=y


CONFIG_NEWLIB_LIBC=y

CONFIG_NEWLIB_LIBC_NANO=n

# LTE link control
CONFIG_LTE_LINK_CONTROL=y
CONFIG_LTE_NETWORK_MODE_LTE_M=y
CONFIG_LTE_AUTO_INIT_AND_CONNECT=n

CONFIG_LTE_LOCK_BANDS=y
CONFIG_LTE_LOCK_BAND_MASK="0000000001000000000000000000"

# Network
CONFIG_NETWORKING=y
CONFIG_NET_NATIVE=n
CONFIG_NET_SOCKETS=y
CONFIG_NET_SOCKETS_OFFLOAD=y

# PDN library
CONFIG_PDN=y
CONFIG_PDN_SYS_INIT=n
CONFIG_PDN_DEFAULTS_OVERRIDE=y
CONFIG_PDN_DEFAULT_APN="myapn"
CONFIG_PDN_DEFAULT_FAM_IPV4=y
CONFIG_PDN_DEFAULT_AUTH_CHAP=y
CONFIG_PDN_DEFAULT_USERNAME="username"
CONFIG_PDN_DEFAULT_PASSWORD="password"


CONFIG_AGPS_OFFLINE_FLG=y


CONFIG_HEAP_MEM_POOL_SIZE=29696

# for debug
CONFIG_DEBUG_OPTIMIZATIONS=y
CONFIG_DEBUG_THREAD_INFO=y

CONFIG_OPENOCD_SUPPORT=y
CONFIG_MAIN_STACK_SIZE=8192
CONFIG_PRIVILEGED_STACK_SIZE=1024
CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=4096


# Flash
CONFIG_SPI=y
CONFIG_FLASH=y

# I2C
CONFIG_I2C_NRFX=y
CONFIG_I2C=y

#IMU
CONFIG_SENSOR=y
CONFIG_ICM42605=y
CONFIG_ICM42605_TRIGGER_NONE=y


# json
CONFIG_JSON_LIBRARY=y

CONFIG_NEWLIB_LIBC_FLOAT_PRINTF=y

# for Zmod library
CONFIG_FPU=y
CONFIG_FPU_SHARING=y
CONFIG_FP_HARDABI=y

CONFIG_CPU_LOAD=y

CONFIG_DATE_TIME=y


CONFIG_APP_VERSION="v0.0.4"

CONFIG_DEVELOP_MODE=y

CONFIG_CJSON_LIB=y
CONFIG_FOTA_DOWNLOAD=y
CONFIG_FOTA_SOCKET_RETRIES=5

#DFU 
CONFIG_DFU_TARGET=y

# MCUBOOT
CONFIG_BOOTLOADER_MCUBOOT=y
CONFIG_MCUBOOT_IMG_MANAGER=y

# Image manager
CONFIG_IMG_MANAGER=y
CONFIG_IMG_ERASE_PROGRESSIVELY=y

# Download client
CONFIG_DOWNLOAD_CLIENT_STACK_SIZE=4096
CONFIG_DOWNLOAD_CLIENT_BUF_SIZE=2048
CONFIG_DOWNLOAD_CLIENT_HTTP_FRAG_SIZE_1024=y
CONFIG_DOWNLOAD_CLIENT_RANGE_REQUESTS=n
CONFIG_DOWNLOAD_CLIENT_LOG_LEVEL_DBG=y
CONFIG_DOWNLOAD_CLIENT_LOG_HEADERS=y
CONFIG_DOWNLOAD_CLIENT_TCP_SOCK_TIMEO_MS=600000 


# DFU Target
CONFIG_DFU_TARGET_STREAM=y
CONFIG_DFU_TARGET_FULL_MODEM=y

# Full modem firmware from external flash support
CONFIG_FMFU_FDEV=y
CONFIG_CDDL_GEN=y

#SPI NOR
CONFIG_SPI_NOR=y

#Stream flash
CONFIG_STREAM_FLASH=y
CONFIG_STREAM_FLASH_ERASE=y

#libmodem
CONFIG_NRF_MODEM_LIB_SYS_INIT=n

#Prevalidation is not yet supported by the modem firmware, so skip it for now.
CONFIG_FMFU_FDEV_SKIP_PREVALIDATION=n

CONFIG_NO_OPTIMIZATIONS=y
CONFIG_EXTRA_EXCEPTION_INFO=y
CONFIG_NCS_SAMPLES_DEFAULTS=n

# Crypto
CONFIG_OBERON_BACKEND=y
CONFIG_NORDIC_SECURITY_BACKEND=y
# Disable all non-used crypto
CONFIG_NRF_SECURITY_RNG=n
CONFIG_MBEDTLS_AES_C=n
CONFIG_MBEDTLS_CHACHA20_C=n
CONFIG_MBEDTLS_POLY1305_C=n
CONFIG_MBEDTLS_ECP_C=n
CONFIG_MBEDTLS_RSA_C=n
CONFIG_MBEDTLS_DHM_C=n
CONFIG_MBEDTLS_SHA1_C=n
CONFIG_MBEDTLS_SHA384_C=n
CONFIG_MBEDTLS_SHA512_C=n
CONFIG_MBEDTLS_GCM_C=n
# This is the one we need
CONFIG_MBEDTLS_SHA256_C=y


scenarIo 1:

Download client can download in debug mode, segger RTT log enabled

scenario 2: 

Download client can't download in non debug mode(debugger connection removed), segger RTT log enabled

why scenario 2 is failing, what causing the problem? 

Best Regards

Praveen Deshmane

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