[New-bugs-announce] [issue3905] subprocess failing in GUI applications on Windows

Todd Whiteman report at bugs.python.org
Fri Sep 19 01:07:02 CEST 2008

New submission from Todd Whiteman <twhitema at yahoo.com.au>:

I'm getting a 'The handle is invalid' error when using subprocess.Popen
in Python 2.5 (and 2.6). If any of the stdio handles are somehow invalid
or not real io handles (fd is not 0, 1 or 2), and you are not telling
subprocess to PIPE all of the handles, then subprocess throws the
following exception.

The easiest way to reproduce this is using run PythonWin from a Windows
Command Prompt:
and then use the following 2 subprocess code lines below:

import subprocess
p = subprocess.Popen(["python", "-c", "print 32"], stdin=None,
stdout=subprocess.PIPE, stderr=subprocess.PIPE)
Traceback (most recent call last):
  File "<interactive input>", line 1, in <module>
  File "C:\Python26\lib\subprocess.py", line 588, in init_
    errread, errwrite) = self._get_handles(stdin, stdout, stderr)
  File "C:\Python26\lib\subprocess.py", line 703, in _get_handles
    p2cread = self._make_inheritable(p2cread)
  File "C:\Python26\lib\subprocess.py", line 748, in _make_inheritable
WindowsError: [Error 6] The handle is invalid

Specifying PIPE for all subprocess.Popen handles is the only way I've
found to get around this problem:

p = subprocess.Popen(["python", "-c", "print 32"],
stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
('32\r\n', '')

components: Windows
messages: 73408
nosy: trentm, twhitema
severity: normal
status: open
title: subprocess failing in GUI applications on Windows
versions: Python 2.5, Python 2.6

Python tracker <report at bugs.python.org>

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