BUG: Allow IOErrors when attempting to retrieve default client encoding.

doc/source/whatsnew/v0.23.2.txt

@@ -65,7 +65,7 @@ Bug Fixes
 **I/O**
 
 - Bug in :func:`read_csv` that caused it to incorrectly raise an error when ``nrows=0``, ``low_memory=True``, and ``index_col`` was not ``None`` (:issue:`21141`)
--
+- Bug in :meth:`detect_client_encoding` where potential IOError goes unhandled when importing in a mod_wsgi process due to restricted access to stdout. (:issue:`21552`)
 -
 
 **Plotting**

pandas/io/formats/console.py

@@ -21,7 +21,7 @@ def detect_console_encoding():
     encoding = None
     try:
         encoding = sys.stdout.encoding or sys.stdin.encoding
-    except AttributeError:
+    except (AttributeError, IOError):
         pass
 
     # try again for something better

pandas/tests/io/formats/test_console.py

@@ -0,0 +1,34 @@
+import pytest
+from functools import partial
+
+from pandas.io.formats.console import detect_console_encoding, locale
+
+
+def mock_raises_exception(error=Exception):
+    raise error
+
+
+def test_detect_console_encoding_stdout(monkeypatch):
+    monkeypatch.setattr('sys.stdin.encoding', '')
+    monkeypatch.setattr('sys.stdout.encoding', 'foo')
+    assert detect_console_encoding() == 'foo'
+
+
+def test_detect_console_encoding_stdin(monkeypatch):
+    monkeypatch.setattr('sys.stdout.encoding', '')
+    monkeypatch.setattr('sys.stdin.encoding', 'foo')
+    assert detect_console_encoding() == 'foo'
+
+
+@pytest.mark.parametrize('error', [AttributeError, IOError])
+def test_detect_console_encoding_stdout_error_uses_locale(monkeypatch, error):
+    monkeypatch.setattr('locale.getpreferredencoding', lambda: 'foo')
+    monkeypatch.setattr('sys.stdout', partial(mock_raises_exception, error))
+    assert detect_console_encoding() == 'foo'
+
+
+def test_detect_console_encoding_sys_default_encoding(monkeypatch):
+    monkeypatch.setattr('locale.getpreferredencoding', mock_raises_exception)
+    monkeypatch.setattr('sys.stdout', mock_raises_exception)
+    monkeypatch.setattr('sys.getdefaultencoding', lambda: 'sysDefaultEncoding')
+    assert detect_console_encoding() == 'sysDefaultEncoding'