From d42f58c943ad66c17fb25da87bc8bacaff438886 Mon Sep 17 00:00:00 2001
From: Oleg Iarygin <oleg@arhadthedev.net>
Date: Fri, 10 Feb 2023 19:51:22 +0400
Subject: [PATCH 1/3] Add tests

---
 Lib/test/test_argparse.py | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/Lib/test/test_argparse.py b/Lib/test/test_argparse.py
index cabb2f837693ff..0a2e5e4a2acede 100644
--- a/Lib/test/test_argparse.py
+++ b/Lib/test/test_argparse.py
@@ -1,5 +1,7 @@
 # Author: Steven J. Bethard <steven.bethard@gmail.com>.
 
+import contextlib
+import functools
 import inspect
 import io
 import operator
@@ -35,6 +37,35 @@ def getvalue(self):
         return self.buffer.raw.getvalue().decode('utf-8')
 
 
+class StdStreamTest(unittest.TestCase):
+
+    def test_skip_invalid_stderr(self):
+        parser = argparse.ArgumentParser()
+        with (
+            contextlib.redirect_stderr(None),
+            mock.patch('argparse._sys.exit')
+        ):
+            parser.exit(status=0, message='foo')
+
+    def test_skip_invalid_stdout(self):
+        parser = argparse.ArgumentParser()
+        for func in (
+            parser.print_usage,
+            parser.print_help,
+            functools.partial(parser.parse_args, ['-h'])
+        ):
+            with (
+                self.subTest(func=func),
+                contextlib.redirect_stdout(None),
+                # argparse uses stderr as a fallback
+                StdIOBuffer() as mocked_stderr,
+                contextlib.redirect_stderr(mocked_stderr),
+                mock.patch('argparse._sys.exit'),
+            ):
+                func()
+                self.assertRegex(mocked_stderr.getvalue(), r'usage:')
+
+
 class TestCase(unittest.TestCase):
 
     def setUp(self):

From 1e3fb87dd26bc9228461c392e87c8ebd7d08ad58 Mon Sep 17 00:00:00 2001
From: Oleg Iarygin <oleg@arhadthedev.net>
Date: Thu, 9 Feb 2023 22:27:19 +0400
Subject: [PATCH 2/3] Make argparse silent on `sys.stderr` set to `None`

---
 Lib/argparse.py                                             | 6 +++---
 .../Library/2023-02-09-22-24-34.gh-issue-101640.oFuEpB.rst  | 2 ++
 2 files changed, 5 insertions(+), 3 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2023-02-09-22-24-34.gh-issue-101640.oFuEpB.rst

diff --git a/Lib/argparse.py b/Lib/argparse.py
index 240625ff01084e..998d01d2cfb1f1 100644
--- a/Lib/argparse.py
+++ b/Lib/argparse.py
@@ -2598,9 +2598,9 @@ def print_help(self, file=None):
 
     def _print_message(self, message, file=None):
         if message:
-            if file is None:
-                file = _sys.stderr
-            file.write(message)
+            file = file or _sys.stderr
+            if file is not None:
+                file.write(message)
 
     # ===============
     # Exiting methods
diff --git a/Misc/NEWS.d/next/Library/2023-02-09-22-24-34.gh-issue-101640.oFuEpB.rst b/Misc/NEWS.d/next/Library/2023-02-09-22-24-34.gh-issue-101640.oFuEpB.rst
new file mode 100644
index 00000000000000..57c45e88cbec52
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2023-02-09-22-24-34.gh-issue-101640.oFuEpB.rst
@@ -0,0 +1,2 @@
+:class:`argparse.ArgumentParser` no longer tries to use :data:`sys.stderr`
+when it is set to ``None``. Patch by Oleg Iarygin.

From 182350cef64b55e35f9ed997691586f770a8b2ba Mon Sep 17 00:00:00 2001
From: Oleg Iarygin <oleg@arhadthedev.net>
Date: Sat, 6 May 2023 22:32:19 +0400
Subject: [PATCH 3/3] Apply suggestions from code review

Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>
---
 Lib/argparse.py                                               | 4 +++-
 .../Library/2023-02-09-22-24-34.gh-issue-101640.oFuEpB.rst    | 3 +--
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/Lib/argparse.py b/Lib/argparse.py
index 24b32bf539d541..68089a5c1e80b0 100644
--- a/Lib/argparse.py
+++ b/Lib/argparse.py
@@ -2606,8 +2606,10 @@ def print_help(self, file=None):
     def _print_message(self, message, file=None):
         if message:
             file = file or _sys.stderr
-            if file is not None:
+            try:
                 file.write(message)
+            except (AttributeError, OSError):
+                pass
 
     # ===============
     # Exiting methods
diff --git a/Misc/NEWS.d/next/Library/2023-02-09-22-24-34.gh-issue-101640.oFuEpB.rst b/Misc/NEWS.d/next/Library/2023-02-09-22-24-34.gh-issue-101640.oFuEpB.rst
index 57c45e88cbec52..917cf0f97b9e06 100644
--- a/Misc/NEWS.d/next/Library/2023-02-09-22-24-34.gh-issue-101640.oFuEpB.rst
+++ b/Misc/NEWS.d/next/Library/2023-02-09-22-24-34.gh-issue-101640.oFuEpB.rst
@@ -1,2 +1 @@
-:class:`argparse.ArgumentParser` no longer tries to use :data:`sys.stderr`
-when it is set to ``None``. Patch by Oleg Iarygin.
+:class:`argparse.ArgumentParser` now catches errors when writing messages, such as when :data:`sys.stderr` is ``None``. Patch by Oleg Iarygin.