Errors when upgrading SDK to 2.8.0

[MOHAMED AHMED ALI MAHMOUD ELSABAGH]

I am trying to upgrade my project which is previously build with NRF connect SDK 2.6.1 to 2.8.0

I am getting this error while building

warning: NCS_SAMPLE_MCUMGR_BT_OTA_DFU (defined at
E:/ncs/v2.8.0/nrf\samples\common\mcumgr_bt_ota_dfu/Kconfig:9) was assigned the value 'y' but got the
value 'n'. Check these unsatisfied dependencies: BOOTLOADER_MCUBOOT (=n). See
docs.zephyrproject.org/.../kconfig.html and/or look up
NCS_SAMPLE_MCUMGR_BT_OTA_DFU in the menuconfig/guiconfig interface. The Application Development
Primer, Setting Configuration Values, and Kconfig - Tips and Best Practices sections of the manual
might be helpful too.

in my prj.conf I already have 

# Enable mcumgr.
CONFIG_MCUMGR=y
# Ensure an MCUboot-compatible binary is generated.
CONFIG_BOOTLOADER_MCUBOOT=y
CONFIG_NCS_SAMPLE_MCUMGR_BT_OTA_DFU=y
CONFIG_SECURE_BOOT=y
CONFIG_IMG_MANAGER=y
CONFIG_MCUBOOT_IMG_MANAGER=y
CONFIG_IMG_ERASE_PROGRESSIVELY=y

[MOHAMED AHMED ALI MAHMOUD ELSABAGH]

I am also getting this errors

warning: Deprecated symbol PLATFORM_SPECIFIC_INIT is enabled.


warning: Deprecated symbol POSIX_CLOCK is enabled.


E:/project/prj.conf:146: warning: attempt to assign the value 'n' to the undefined symbol MCUMGR_TRANSPORT_BT_AUTHEN

I have no PLATFORM_SPECIFIC_INIT or POSIX_CLOCK defined anywhere in the project