LinkServer/MCX-A346: Ee(42). Could not connect to core.

[ygrayne]

After using this successfully hundreds of times, I have lost the ability to flash or erase the FRDM-MCXA346, getting the dreaded error "Ee(42). Could not connect to core.".

linkserver -l 5 flash mcxa346:frdm-mcxa346 load --erase-all signalsync.elf

The debug-level output is attached.

LinkServer_25.9.134, Windows 11

I have searched the forums and have found many similar reports and questions, but none of the solutions has worked for this specific board. The probe as well as the VCOM port show up in the Windows device manager. The MCU-Link firmware is up-to-date. All jumpers are in their default configuration (ie. as out of the box).

I am working on the bare metal (no IDE) and want to use LinkServer from the command-line (ie. integrated into my build system).

How do I get back control? Thanks in advance.

[ygrayne]

Oops, here's the file with the command output.

[Alice_Yang]

Hello @ygrayne 

Thank you for contacting us.
Please try using the LinkFlash GUI program first.
This will allow you to view the log and commands used during the process.

Thank you!

BR

Alice

[ygrayne]

Hi Alice, thank you. Since LinkFlash is merely a front-end to the command-line program, it produces the same log-output as the one already provided via attached file.

Without specifying a log-level:

linkserver flash mcxa346:frdm-mcxa346 load --erase-all signalsync.elf                 
INFO: Exact match for mcxa346:frdm-mcxa346 found
INFO: Selected device MCXA346:FRDM-MCXA346
INFO: Getting available probes
INFO: Selected probe #1 UFHKAWQFL2TTQ (MCU-LINK FRDM-MCXA346 (r0E4) CMSIS-DAP V3.165)
INFO: MCU-Link firmware update `check`: Probe ([UFHKAWQFL2TTQ] [MCU-LINK FRDM-MCXA346 (r0E4) CMSIS-DAP V3.165]) is already running the same firmware version as the included firmware version [3.165]
Firmware update `check`: not required - forced update can be performed using: `LinkServer probe #1 update forced`
INFO: Selected device matches probe's target identification info
Ns: LinkServer RedlinkMulti Driver v25.9 (Sep 25 2025 19:34:03 - crt_emu_cm_redlink.exe build 1103)
Pc: (  0) Reading remote configuration
Wc(03). No cache support.
Nc: Found generic directory XML file in C:\Users\gray\AppData\Local\Temp\tmpvcbt5mqg\crt_directory.xml
Pc: (  5) Remote configuration complete
Nc: Reconnected to existing LinkServer process.
Nc: Connecting to probe 1 core 0 (using server started externally) reports:
    'Ee(42). Could not connect to core.'
Nc: Retrying...
Nc: Reconnected to existing LinkServer process.
Nc: Server OK but no connection to probe 1 core 0 (after 3 attempts) - Ee(42). Could not connect to core.
Ed:02: Failed on connect: Ee(42). Could not connect to core.
Et:31: No connection to chip's debug port
Pc: (100) Target Operation Failed
CRITICAL: Critical error
ERRMSG: Exception: Flash operation exited with code 1

 Debug-level log:

linkserver -l 5 flash mcxa346:frdm-mcxa346 load --erase-all signalsync.elf
[211]DEBUG:asyncio: Using proactor: IocpProactor
[807]INFO:launcher.cli.utils.funcs: Exact match for mcxa346:frdm-mcxa346 found
[808]INFO:launcher.cli.utils.click: Selected device MCXA346:FRDM-MCXA346
[836]DEBUG:launcher.core.redlinkserv: Starting redlinkserv: C:\NXP\LinkServer_25.9.134\binaries\redlinkserv.exe ['--port', '11111', '--telnetport', '12223', '--no-telnet-defaults']
[841]DEBUG:launcher.core.probeboot: Listing usb devices
[841]DEBUG:launcher.core.utils: Subprocess exec: powershell ['-ExecutionPolicy', 'Bypass', '-NonInteractive', '-NoLogo', '-File', 'C:\\NXP\\LinkServer_25.9.134\\binaries\\Scripts\\listusb.ps1']
[856]DEBUG:launcher.core.utils: Connecting to redlinkserv (localhost:12223)
[1399]DEBUG:launcher.core.probeboot: Found 30 USB devices
[2902]DEBUG:launcher.core.utils: Connected to redlinkserv (localhost:12223)
[2902]DEBUG:launcher.core.redlinkserv: [read] 
[2902]INFO:launcher.cli.utils.click: Getting available probes
[2902]DEBUG:launcher.core.redlinkserv: [write] probelist
[3063]DEBUG:launcher.core.redlinkserv: [read] Index = 1
Manufacturer = NXP Semiconductors
Description = MCU-LINK FRDM-MCXA346 (r0E4) CMSIS-DAP V3.165
Serial Number = UFHKAWQFL2TTQ
VID:PID = 1FC9:0143
Path = 0001:0022:00
[3063]DEBUG:launcher.core.redlinkserv: Probe capabs: ProbeCapabs.DEBUG|VCOM|SIO
[3063]DEBUG:launcher.core.redlinkserv: [write] ProbeOpenByIndex 1
[3074]DEBUG:launcher.core.redlinkserv: [read] Probe Handle 1 Open
[3074]DEBUG:launcher.core.redlinkserv: [write] ProbeDapInfo 1
[3075]DEBUG:launcher.core.redlinkserv: [read] Vendor Name = NXP Semiconductors
Product Name = MCU-Link CMSIS-DAP V3.165
Serial Number = UFHKAWQFL2TTQ
CMSIS-DAP Version = 2.1.1
Target Device Vendor = NXP
Target Device Name = MCXA346VLQ
Target Board Vendor = NXP
Target Board Name = FRDM-MCXA346
Firmware Version = 3.165
Capabilities =
        SWD+JTAG
        SWO UART 2048 byte buffer
        Atomic
        Test Domain Timer Frequency 150000000
        UART USB COM Port
        Packets 512 bytes x 4
[3076]DEBUG:launcher.core.redlinkserv: [write] ProbeCloseByIndex 1
[3076]DEBUG:launcher.core.redlinkserv: [read] Probe Handle 1 Closed
[3665]INFO:launcher.cli.utils.click: Selected probe #1 UFHKAWQFL2TTQ (MCU-LINK FRDM-MCXA346 (r0E4) CMSIS-DAP V3.165)
[3666]INFO:launcher.core.redlinkserv: MCU-Link firmware update `check`: Probe ([UFHKAWQFL2TTQ] [MCU-LINK FRDM-MCXA346 (r0E4) CMSIS-DAP V3.165]) is already running the same firmware version as the included firmware version [3.165]
Firmware update `check`: not required - forced update can be performed using: `LinkServer probe #1 update forced`
[3668]INFO:launcher.cli.utils.click: Selected device matches probe's target identification info
[3668]DEBUG:launcher.core.redlinkserv: [write] probeopenbyindex 1
[3679]DEBUG:launcher.core.redlinkserv: [read] Probe Handle 1 Open
[3679]DEBUG:launcher.core.redlinkserv: [write] wireswdconnect 1
[3901]DEBUG:launcher.core.redlinkserv: [read] Error: Wire Ack Fault - target connected?
[3901]DEBUG:launcher.core.redlinkserv: [write] new
[3901]DEBUG:launcher.core.redlinkserv: [read]
[3901]DEBUG:launcher.core.redlinkserv: [write] a% = 1
[3901]DEBUG:launcher.core.redlinkserv: [read]
[3901]DEBUG:launcher.core.redlinkserv: [write] load "C:\NXP\LinkServer_25.9.134\binaries\ToolScripts\LS_preconnect_MCXA3XX.scp"   [3901]DEBUG:launcher.core.redlinkserv: [read] Loading "LS_preconnect_MCXA3XX.scp"
[3901]DEBUG:launcher.core.redlinkserv: [write] run
[4237]DEBUG:launcher.core.redlinkserv: [read] Probe Handle 1 Open
Reset pin state: 01
Error: Wire Ack Fault - target connected?
Error: Wire Ack Fault - target connected?
Issuing Debug Session Request... 7

Error: Wire not connected
Error: Wire Ack Fault - target connected?
[4237]DEBUG:launcher.core.redlinkserv: [write] new
[4237]DEBUG:launcher.core.redlinkserv: [read]
[4237]DEBUG:launcher.core.redlinkserv: [write] coreconfig 1
[4237]DEBUG:launcher.core.redlinkserv: [read-partial] b'Error: Wire not connected\n'
[4237]DEBUG:launcher.core.redlinkserv: [read] Error: Wire not connected
[4237]DEBUG:launcher.core.redlinkserv: [write] corelist 1
[4238]DEBUG:launcher.core.redlinkserv: [read] Error: Wire Ack Fault - target connected?
[4239]DEBUG:launcher.core.stub: Wrote stub XML: C:\Users\gray\AppData\Local\Temp\tmpi0ryp53q\crt_directory.xml
[4240]DEBUG:launcher.core.stub: Wrote stub XML: C:\Users\gray\AppData\Local\Temp\tmpi0ryp53q\part.xml
[4255]DEBUG:launcher.core.stub: GDB server args: ['--redlink-port', '11111', '--flash-dir', 'C:\\NXP\\LinkServer_25.9.134\\binaries\\Flash', '-x', 'C:\\Users\\gray\\AppData\\Local\\Temp\\tmpi0ryp53q', '-pMCXA346', '--vendor', 'NXP', '-g', '--cache', 'dis', '--probeserial', 'UFHKAWQFL2TTQ', '--coreindex', '0', '--msg-port', '15555', '--romstall', '0x4009123C', '--flash-mass-load-exec', 'C:\\Users\\gray\\Projects\\oberon\\dev\\oberon-rtk\\examples\\v2.x\\nxp\\frdm-mcxa346\\SignalSync\\signalsync.elf']
Ns: LinkServer RedlinkMulti Driver v25.9 (Sep 25 2025 19:34:03 - crt_emu_cm_redlink.exe build 1103)
Pc: (  0) Reading remote configuration
Wc(03). No cache support.
Nc: Found generic directory XML file in C:\Users\gray\AppData\Local\Temp\tmpi0ryp53q\crt_directory.xml
Pc: (  5) Remote configuration complete
Nc: Reconnected to existing LinkServer process.
Nc: Connecting to probe 1 core 0 (using server started externally) reports:
    'Ee(42). Could not connect to core.'
Nc: Retrying...
Nc: Reconnected to existing LinkServer process.
Nc: Server OK but no connection to probe 1 core 0 (after 3 attempts) - Ee(42). Could not connect to core.
Ed:02: Failed on connect: Ee(42). Could not connect to core.
Et:31: No connection to chip's debug port
Pc: (100) Target Operation Failed
[7239]DEBUG:launcher.core.stub: Stub-flash stdout socket closed (15555)
[7242]DEBUG:launcher.core.redlinkserv: [write] exit
[7242]DEBUG:launcher.core.redlinkserv: Waiting for redlinkserv to close
[7563]DEBUG:launcher.core.redlinkserv: Redlinkserv has closed
[7564]CRITICAL:__main__: Critical error
Traceback (most recent call last):
  File "__main__.py", line 40, in <module>
  File "click\core.py", line 1130, in __call__
  File "click\core.py", line 1055, in main
  File "click\core.py", line 1657, in invoke
  File "click\core.py", line 1657, in invoke
  File "click\core.py", line 1404, in invoke
  File "click\core.py", line 760, in invoke
  File "launcher\cli\utils\funcs.py", line 153, in wrapper
  File "asyncio\runners.py", line 195, in run
  File "asyncio\runners.py", line 118, in run
  File "asyncio\base_events.py", line 719, in run_until_complete
  File "launcher\cli\utils\click.py", line 135, in wrapper
  File "launcher\cli\cmd\flash.py", line 52, in wrapper
  File "launcher\cli\cmd\flash.py", line 88, in cmd_flash_load
  File "launcher\core\stub.py", line 823, in run_flash
Exception: Flash operation exited with code 1

As you see, the process fails at:  

wireswdconnect 1

Actually twice, since also the pre-connect script issues the same command. It appears as if the SWD pins are disabled at the point when LinkServer attempts to access them. As I understand, LinkServer should prevent the current program in flash to run before it accesses the SWD interface ("connnect while in reset"). I have tried to modify the pre-connect script accordingly, but have not been successful, due to my limited knowledge here.

Thank you.

[Alice_Yang]

Hello @ygrayne 

Thank you for your response.

If the board was previously functioning but has stopped working, please enter ISP mode, perform a full chip erase, and then test again.

Thank you!

BR

Alice

[ygrayne]

Hi Alice, thanks. How do I perform a full chip erase in ISP mode?

This results in the same error:

linkserver flash mcxa346:frdm-mcxa346 erase

I suspect LinkServer does a reset, which takes the MCU out of ISP mode and starts the program in flash memory, before LinkServer can get hold of the SWD pins.

I have looked at FlashMagic, but the MCX-A346 is not supported. So I cannot tell if this utility would solve the problem.

Thanks.

[Alice_Yang]

Hello @ygrayne 

Thanks for your reply.
To enter ISP mode on the MCXA device, please use the latest version SEC 25.09.

Download from:

https://www.nxp.com/design/design-center/software/development-software/mcuxpresso-software-and-tools... 

Thank you.

BR

Alice

[ygrayne]

Hi Alice, thank you, I  have been able to restore core access using SEC 25.09. I have used a J-Link probe to connect to the target.