west flash with Renesas Flash Programmer not working under Windows

[n3rd4i]

Describe the bug

Flashing the XIAO RA4M1 which comes with stock bootloader does not work under Windows OS. The setup requires usage of external "Renesas Flash Programmer" tool.

Regression

• This is a regression.

Steps to reproduce

1. Install Zephyr v4.3.0 development environment under Windows following Getting Started Guide.
2. west build -b xiao_ra4m1 samples/hello_world
3. west flash

Relevant log output

-- west flash: rebuilding
ninja: no work to do.
-- west flash: using runner rfp
-- runners.rfp: Flashing file: C:\Users\andrei\zephyrproject\zephyr\build\zephyr\zephyr.hex
Traceback (most recent call last):
  File "<frozen runpy>", line 198, in _run_module_as_main
  File "<frozen runpy>", line 88, in _run_code
  File "C:\Users\andrei\zephyrproject\.venv\Scripts\west.exe\__main__.py", line 7, in <module>
  File "C:\Users\andrei\zephyrproject\.venv\Lib\site-packages\west\app\main.py", line 1199, in main
    app.run(argv or sys.argv[1:])
  File "C:\Users\andrei\zephyrproject\.venv\Lib\site-packages\west\app\main.py", line 278, in run
    self.run_command(argv, early_args)
  File "C:\Users\andrei\zephyrproject\.venv\Lib\site-packages\west\app\main.py", line 584, in run_command
    self.run_extension(args.command, argv)
  File "C:\Users\andrei\zephyrproject\.venv\Lib\site-packages\west\app\main.py", line 739, in run_extension
    self.cmd.run(args, unknown, self.topdir, manifest=self.manifest,
  File "C:\Users\andrei\zephyrproject\.venv\Lib\site-packages\west\commands.py", line 200, in run
    self.do_run(args, unknown)
  File "C:\Users\andrei\zephyrproject\zephyr\scripts\west_commands\flash.py", line 32, in do_run
    do_run_common(self, my_args, runner_args, domain_file=domains_file)
  File "C:\Users\andrei\zephyrproject\zephyr\scripts/west_commands\run_common.py", line 353, in do_run_common
    prev_runner = do_run_common_image(command, user_args, user_runner_args, used_cmds,
                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\andrei\zephyrproject\zephyr\scripts/west_commands\run_common.py", line 528, in do_run_common_image
    runner.run(command_name)
  File "C:\Users\andrei\zephyrproject\zephyr\scripts/west_commands\runners\core.py", line 766, in run
    self.do_run(command, **kwargs)
  File "C:\Users\andrei\zephyrproject\zephyr\scripts/west_commands\runners\rfp.py", line 139, in do_run
    self.do_flash(**kwargs)
  File "C:\Users\andrei\zephyrproject\zephyr\scripts/west_commands\runners\rfp.py", line 177, in do_flash
    self.check_call(cmd)
  File "C:\Users\andrei\zephyrproject\zephyr\scripts/west_commands\runners\core.py", line 913, in check_call
    subprocess.check_call(cmd, **kwargs)
  File "C:\Program Files\WindowsApps\PythonSoftwareFoundation.Python.3.12_3.12.2800.0_x64__qbz5n2kfra8p0\Lib\subprocess.py", line 408, in check_call
    retcode = call(*popenargs, **kwargs)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Program Files\WindowsApps\PythonSoftwareFoundation.Python.3.12_3.12.2800.0_x64__qbz5n2kfra8p0\Lib\subprocess.py", line 389, in call
    with Popen(*popenargs, **kwargs) as p:
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Program Files\WindowsApps\PythonSoftwareFoundation.Python.3.12_3.12.2800.0_x64__qbz5n2kfra8p0\Lib\subprocess.py", line 1026, in __init__
    self._execute_child(args, executable, preexec_fn, close_fds,
  File "C:\Program Files\WindowsApps\PythonSoftwareFoundation.Python.3.12_3.12.2800.0_x64__qbz5n2kfra8p0\Lib\subprocess.py", line 1462, in _execute_child
    args = list2cmdline(args)
           ^^^^^^^^^^^^^^^^^^
  File "C:\Program Files\WindowsApps\PythonSoftwareFoundation.Python.3.12_3.12.2800.0_x64__qbz5n2kfra8p0\Lib\subprocess.py", line 608, in list2cmdline
    for arg in map(os.fsdecode, seq):
               ^^^^^^^^^^^^^^^^^^^^^
  File "<frozen os>", line 859, in fsdecode
TypeError: expected str, bytes or os.PathLike object, not NoneType

Impact

Showstopper – Prevents release or major functionality; system unusable.

Environment

• Windows 11
• zephyr-sdk-0.17.4
• Zephyr v4.3.0

Additional Context

using rfp-cli.exe directly seems to work, e.g.:

1. rfp-cli -port COM16 -device RA -read current.bin
2. rfp-cli -port COM16 -device RA -program build\zephyr\zephyr.hex

[n3rd4i]

Trying to run west flash with specified rfp-cli.exe makes no difference (same output as above), e.g.:
west flash --rfp-cli "C:\Program Files (x86)\Renesas Electronics\Programming Tools\Renesas Flash Programmer V3.21\rfp-cli.exe"