Python script called from VBA called from Python is not working

Question

I maintain an Excel with macro's that download some data from the internet. The downloading is done within Python (I will call this Python A), stored intermediately, and picked up by the Excel again. This Python flow is triggered by a macro within that Excel. Because I have to do this at specific times I wanted to automatize this by using another Python scheduler. The scheduler opens a Nothing fancy, did that before, at least so I thought. The problem I am currently facing is that Python A is not running correctly when triggered from Python B. The Excel macro is running fine. I know that because some files are being exported, which is also done within a macro.

What I have tried so far:

• Running the macro's manually is all fine
• Setting all paths absolute, but that was already the case, so nothing to be improved there.
• Calling the Python B flow from a bat file. This does work (?!)
• Calling the bat from the scheduled flow does not work

Code in VBA:

cmdLine = "python ""path_with_spaces_to_file"" "

lngResult = ShellAndWait(cmdLine, 0, vbNormalFocus, AbandonWait)

Code in Python B to call Macro:

import win32com.client
def func():
    filename_excel = r"filename_to_excel_with_spaces.xlsm"
    xl = win32com.client.DispatchEx('Excel.Application')
    xl.Visible = False

    xl.Workbooks.Open(Filename=filename_excel, ReadOnly=1)

    sheet = xl.ActiveWorkbook.Sheets("Sheetname")

    xl.Application.Run("Macroname")
    xl.DisplayAlerts = False
    xl.Application.Quit()

How I call this function from the scheduler:

subprocess.run(["python3_location.bat", "-c", 'from python_B_file import func; func()'],
                stdout=subprocess.PIPE,
                cwd=r"path_to_python_B_file",
                universal_newlines=True,
                timeout=60)

I see an extra cmd window popping up, but there is no new file downloaded. I cannot see an error message

Answer 1

Trying out different things, I found out that in the normal namespace the command python refers to the system defaults Python 2.7 installation, while the Python B is 3.7. Python A code was not Python 3 compatible (something with urllib, easily solved to something working in both Python versions). Calling the Excel macro from Python B changed the namespace somehow, and the ShellAndWait command referred to Python 3.7.