Hey there, let's tackle this missing pythonw.exe issue together—it's a common hiccup, but we've got solid fixes and workarounds for you:

First, Verify & Troubleshoot the Installation #

• Double-check your install path: pythonw.exe lives right alongside python.exe in your Python 3.9 root directory (usually C:\Users\<YourUsername>\AppData\Local\Programs\Python\Python39\ or your custom install folder). It's easy to accidentally look in the wrong subfolder, so confirm you're checking the main directory.
• Reinstall with correct options: When you reinstall Python 3.9, make sure to:
  1. Select "Customize installation" instead of the default.
  2. In the "Optional Features" step, ensure IDLE is checked (since pythonw.exe is tied to the IDLE environment).
  3. Finish the installation—this should force the creation of pythonw.exe.
• Add Python folder to antivirus exclusions: Even if you disabled Malwarebytes and Windows Defender during install, their real-time protection might still flag the file post-install. Add your entire Python 3.9 directory to both tools' exclusion lists to prevent future deletions.

If pythonw.exe Still Won't Show Up: Alternatives to Run Scripts in the Background #

You don't strictly need pythonw.exe to run scripts without a console window—here are reliable alternatives:

• Use python.exe with the -w flag: This replicates exactly what pythonw.exe does. Just run:

  python.exe -w your_script.py
  

  The -w flag suppresses the console window, letting your script run silently in the background.
• Schedule via Task Scheduler: For recurring background runs, set up a Windows Task:
  1. Open Task Scheduler > Create Basic Task.
  2. Set your trigger (e.g., daily, on login).
  3. For the action, choose "Start a program", browse to your python.exe, and add the argument:

     -w "C:\Full\Path\To\Your\script.py"
     

  4. Check "Do not start a new instance" in settings for reliability.
• Register as a Windows Service (for long-running scripts): Tools like NSSM (Non-Sucking Service Manager) let you turn your Python script into a persistent background service. Once set up, it'll run automatically on boot without any user intervention.

内容的提问来源于stack exchange，提问作者Paolo Romano