nrfjprog cannot connects to PCA10056

Question

nrfjprog is reporting "Cannot connect to J-Link." while trying to erase on MacOS Catalina 
 Board used to work properly, but attempting to re-connect after a wipe of my MacBook. 
 Log.log is attached. Is there some compatibility issue with Catalina or are there other program installs required besides the nRF-Command-Line-Tools and JLink Driver?

Fullscreen 
 log.log 
 Download 
 
 2019-Dec-06 14:00:39 --------------------------------------------------------------------------------
2019-Dec-06 14:00:39 nrfjprog -f nrf52 --eraseall --log 
2019-Dec-06 14:00:39 nrfjprog version 10.5.0 
2019-Dec-06 14:00:39 --------------------------------------------------------------------------------
2019-Dec-06 14:00:39 nRF_logger_open
2019-Dec-06 14:00:39 nRF_logger_open:	nRFJProg logger opened to callback at address 0X10DF76AB0
2019-Dec-06 14:00:39 nRF_open_dll
2019-Dec-06 14:00:39 nRF_open_dll:	Load library at "/Applications/Nordic Semiconductor/nrfjprog/libjlinkarm_nrf52_nrfjprogdll.dylib".

2019-Dec-06 14:00:39 . nRF52_logger_open
2019-Dec-06 14:00:39 . nRF52_logger_open:	nRFJProg logger opened to callback at address 0X10DFFF130
2019-Dec-06 14:00:39 . nRF52_open_dll
2019-Dec-06 14:00:39 . . Segger_logger_open
2019-Dec-06 14:00:39 . . Segger_logger_open:	nRFJProg logger opened to callback at address 0X10E037C50
2019-Dec-06 14:00:39 . . Segger_open_dll
2019-Dec-06 14:00:39 . . Segger_open_dll:	Load library at "/Applications/SEGGER/JLink/libjlinkarm.6.54.3.dylib".

2019-Dec-06 14:00:39 . . . Segger_dll_version
2019-Dec-06 14:00:39 . . Segger_set_core_data
2019-Dec-06 14:00:39 nRF_enum_emu_snr
2019-Dec-06 14:00:39 . nRF52_enum_emu_snr
2019-Dec-06 14:00:39 . . Segger_enum_emu_snr
2019-Dec-06 14:00:39 . . . Segger_enum_emu_snr
2019-Dec-06 14:00:39 . . . . Segger_get_num_emus
2019-Dec-06 14:00:39 nRF_connect_to_emu_without_snr
2019-Dec-06 14:00:39 . nRF52_connect_to_emu_without_snr
2019-Dec-06 14:00:39 . . Segger_connect_to_emu_without_snr
2019-Dec-06 14:00:39 . . . Segger_is_connected_to_emu
2019-Dec-06 14:00:39 . . . Segger_get_num_emus
2019-Dec-06 14:00:39 . . . Segger_connect_to_emu_without_snr
2019-Dec-06 14:00:39 . . . Segger_connect_to_emu_without_snr:	Segger logging enabled with callback at 0x4530078592.

2019-Dec-06 14:00:40 . . . Segger_connect_to_emu_without_snr:	JLink INFO	T10EC1DC0 001:015.476 
2019-Dec-06 14:00:40 . . . Segger_connect_to_emu_without_snr:	JLink INFO ***** Error: 
2019-Dec-06 14:00:40 . . . Segger_connect_to_emu_without_snr:	JLink INFO	T10EC1DC0 001:016.607 
2019-Dec-06 14:00:40 . . . Segger_connect_to_emu_without_snr:	JLink INFO	Cannot connect to J-Link.
2019-Dec-06 14:00:40 . . . Segger_connect_to_emu_without_snr:	JLink INFO	T10EC1DC0 001:016.966 
2019-Dec-06 14:00:40 . . . Segger_connect_to_emu_without_snr:	JLink INFO	- 1009.845ms returns "Cannot connect to J-Link." 
2019-Dec-06 14:00:40 . . . Segger_connect_to_emu_without_snr:	JLinkARM.dll Open returned error 'Cannot connect to J-Link.'.

2019-Dec-06 14:00:40 nRF_close_dll
2019-Dec-06 14:00:40 . nRF52_close_dll
2019-Dec-06 14:00:40 . . Segger_close
2019-Dec-06 14:00:40 . . . Segger_disconnect_from_emu
2019-Dec-06 14:00:40 . . . . Segger_is_connected_to_emu
2019-Dec-06 14:00:40 . . . . Segger_is_connected_to_emu:	JLink INFO	T10EC1DC0 001:017.589 
2019-Dec-06 14:00:40 . . . . Segger_is_connected_to_emu:	JLink INFO	JLINK_IsOpen() 
2019-Dec-06 14:00:40 . . . . Segger_is_connected_to_emu:	JLink INFO	T10EC1DC0 001:017.737 
2019-Dec-06 14:00:40 . . . . Segger_is_connected_to_emu:	JLink INFO	- 0.223ms returns 0x00 
2019-Dec-06 14:00:40 . . Segger_close:	Freeing Library.

2019-Dec-06 14:00:40 nRF_close_dll:	Freeing Library.

Ken · Answer

Solution:
Do not have a sagger debugger attached while trying to interface to the Dev Board.
nrfjprog cannot determine which sagger is the Nordic Board & which is the other board.
Once I removed the second debugger, everything worked fine.