MATLABPyHost.exe won't start on Windows

Hi,

I've been trying to get MATLAB's 'OutOfProcess' Python support to work on a Windows runner, but I've encountered an issue that I can't get past. This is my workflow:

name: MATLAB Windows OutOfProcess Bug

on:
  push:
    branches: [ main ]
  pull_request:
    branches: [ main ]

jobs:
  main:
    runs-on: 'windows-latest'
    steps:
      - name: Set up MATLAB
        uses: matlab-actions/setup-matlab@v1
      - name: Set up Python
        uses: actions/setup-python@v2
        with:
          python-version: '3.8'
      - name: Create MATLAB script
        run: |
          "pyenv('ExecutionMode', 'OutOfProcess')" | Out-File -FilePath run.m
          "py.list({'Monday','Tuesday','Wednesday','Thursday','Friday'})" | Out-File -FilePath run.m -Append
      - name: Run script
        run: matlab -batch "run"

The output from the last step is:

MATLAB is running in headless mode.  Figure windows will not be displayed.

    Sponsored License -- for use in support of a program or activity sponsored by MathWorks.
    Not for government, commercial or other non-sponsored organizational use.

Caught "std::exception" Exception message is:
Unable to launch Simple server: Unable to launch C:\Program Files\MATLAB\R2021b\interprocess\bin\win64\pycli\MATLABPyHost.exe

because: An error occurred while initializing child process:  While attempting to execute "C:\Program Files\MATLAB\R2021b\interprocess\bin\win64\pycli\MATLABPyHost.exe -mvmInputPipe 138736 0 0 0 0 0 -mvmOutputPipe 0 139588 0 0 0 0": CreateProcessW: The parameter is incorrect

ans = 

  PythonEnvironment with properties:

          Version: "3.8"
       Executable: "C:\hostedtoolcache\windows\Python\3.8.[10](https://github.com/H0R5E/matlab-actions-windows-bug/runs/5096231061#step:5:10)\x64\python.EXE"
          Library: "C:\hostedtoolcache\windows\Python\3.8.10\x64\python38.dll"
             Home: "C:\hostedtoolcache\windows\Python\3.8.10\x64"
           Status: NotLoaded
    ExecutionMode: OutOfProcess

thread_monitor::launch: _beginthreadex failed
ERROR: MATLAB error Exit Status: 0x00000001
Error: Process completed with exit code 1.

I have set up a repo just to test this issue and you can see the outcome here.

I understand that Windows support is not official, as yet, but can you offer me any advice about this issue?

Many thanks,

Mat

matlab-actions / setup-matlab

MATLABPyHost.exe won't start on Windows #26