$ pwd/home/serhiy/py/cpy�thon-3.5$ ./python -vimport _frozen_importlib # frozenimport _imp # builtinimport sys # builtinimport '_warnings' # <class '_frozen_importlib.BuiltinImporter'>import '_thread' # <class '_frozen_importlib.BuiltinImporter'>import '_weakref' # <class '_frozen_importlib.BuiltinImporter'>import '_frozen_importlib_external' # <class '_frozen_importlib.FrozenImporter'>import '_io' # <class '_frozen_importlib.BuiltinImporter'>import 'marshal' # <class '_frozen_importlib.BuiltinImporter'>import 'posix' # <class '_frozen_importlib.BuiltinImporter'>import _thread # previously loaded ('_thread')import '_thread' # <class '_frozen_importlib.BuiltinImporter'>import _weakref # previously loaded ('_weakref')import '_weakref' # <class '_frozen_importlib.BuiltinImporter'># installing zipimport hookimport 'zipimport' # <class '_frozen_importlib.BuiltinImporter'># installed zipimport hookFatal Python error: Py_Initialize: Unable to get the locale encodingTraceback (most recent call last):  File "<frozen importlib._bootstrap>", line 969, in _find_and_load# destroy io  File "<frozen importlib._bootstrap>", line 958, in _find_and_load_unlocked# destroy io  File "<frozen importlib._bootstrap>", line 673, in _load_unlocked# destroy io  File "<frozen importlib._bootstrap_external>", line 658, in exec_module# destroy io  File "<frozen importlib._bootstrap_external>", line 759, in get_code# destroy io  File "<frozen importlib._bootstrap_external>", line 368, in _verbose_message# destroy ioUnicodeEncodeError: 'utf-8' codec can't encode character '\udcff' in position 21: surrogates not allowed# destroy encodingsAborted (core dumped)

And what happens if you leave -v off? Since the failure is in Py_Initialize I want to know if that Py_FatalError trigger is avoided without -v.A possible fix to test is to simply modify importlib._bootstrap._verbose_message to catch UnicodeDecodeError and then print some message saying that there was some undecodable string and just swallow the exception. I just don't know if this is in the right place to prevent Py_Initialize from erroring out.

python without -v is not failed.If wrap message in _bootstrap_external._verbose_message with '!%a'% and in _bootstrap._verbose_message with '%a'% (why _verbose_message is duplicated in _bootstrap and _bootstrap_external?), the output is:...# installing zipimport hook@"import 'zipimport' # <class '_frozen_importlib.BuiltinImporter'>"# installed zipimport hook!'# /home/serhiy/py/cpy\udcffthon-3.5/Lib/encodings/__pycache__/__init__.cpython-35.pyc matches /home/serhiy/py/cpy\udcffthon-3.5/Lib/encodings/__init__.py'!"# code object from '/home/serhiy/py/cpy\\udcffthon-3.5/Lib/encodings/__pycache__/__init__.cpython-35.pyc'"!'# /home/serhiy/py/cpy\udcffthon-3.5/Lib/__pycache__/codecs.cpython-35.pyc matches /home/serhiy/py/cpy\udcffthon-3.5/Lib/codecs.py'!"# code object from '/home/serhiy/py/cpy\\udcffthon-3.5/Lib/__pycache__/codecs.cpython-35.pyc'"@"import '_codecs' # <class '_frozen_importlib.BuiltinImporter'>"@"import 'codecs' # <_frozen_importlib_external.SourceFileLoader object at 0xb70b9aac>"!'# /home/serhiy/py/cpy\udcffthon-3.5/Lib/encodings/__pycache__/aliases.cpython-35.pyc matches /home/serhiy/py/cpy\udcffthon-3.5/Lib/encodings/aliases.py'!"# code object from '/home/serhiy/py/cpy\\udcffthon-3.5/Lib/encodings/__pycache__/aliases.cpython-35.pyc'"@"import 'encodings.aliases' # <_frozen_importlib_external.SourceFileLoader object at 0xb70c81ac>"@"import 'encodings' # <_frozen_importlib_external.SourceFileLoader object at 0xb70b96cc>"!'# /home/serhiy/py/cpy\udcffthon-3.5/Lib/encodings/__pycache__/utf_8.cpython-35.pyc matches /home/serhiy/py/cpy\udcffthon-3.5/Lib/encodings/utf_8.py'!"# code object from '/home/serhiy/py/cpy\\udcffthon-3.5/Lib/encodings/__pycache__/utf_8.cpython-35.pyc'"@"import 'encodings.utf_8' # <_frozen_importlib_external.SourceFileLoader object at 0xb70ccd2c>"@"import '_signal' # <class '_frozen_importlib.BuiltinImporter'>"!'# /home/serhiy/py/cpy\udcffthon-3.5/Lib/encodings/__pycache__/latin_1.cpython-35.pyc matches /home/serhiy/py/cpy\udcffthon-3.5/Lib/encodings/latin_1.py'!"# code object from '/home/serhiy/py/cpy\\udcffthon-3.5/Lib/encodings/__pycache__/latin_1.cpython-35.pyc'"@"import 'encodings.latin_1' # <_frozen_importlib_external.SourceFileLoader object at 0xb70cf54c>"!'# /home/serhiy/py/cpy\udcffthon-3.5/Lib/__pycache__/io.cpython-35.pyc matches /home/serhiy/py/cpy\udcffthon-3.5/Lib/io.py'!"# code object from '/home/serhiy/py/cpy\\udcffthon-3.5/Lib/__pycache__/io.cpython-35.pyc'"...Verbose non-ascii message is written before importing codecs.

Before importing the io module sys.stderr is stdprinter. It always encodes written string to UTF-8. Proposed patch makes it to use the backslashreplace error handler.In future perhaps we could implement stdprinter in Python.

> Before importing the io module sys.stderr is stdprinter. It always encodes written string to UTF-8. Proposed patch makes it to use the backslashreplace error handler.I like this solution. stdprinter is supposed to be replaced quickly.But we may need something else to escape non-encodable characters in the filename when sys.stdout is a TextIOWrapper using the strict error handler.

New changeset6347b154dd67 by Serhiy Storchaka in branch '3.4':Issue#25182: The stdprinter (used as sys.stderr before the io module ishttps://hg.python.org/cpython/rev/6347b154dd67New changesete8b6c6c433a4 by Serhiy Storchaka in branch '3.5':Issue#25182: The stdprinter (used as sys.stderr before the io module ishttps://hg.python.org/cpython/rev/e8b6c6c433a4New changeset0b0945c8de36 by Serhiy Storchaka in branch 'default':Issue#25182: The stdprinter (used as sys.stderr before the io module ishttps://hg.python.org/cpython/rev/0b0945c8de36

Thank you for the review Victor.> But we may need something else to escape non-encodable characters in the filename when sys.stdout is a TextIOWrapper using the strict error handler.This is not related to this issue. sys.stderr uses backslashreplace.

> This is not related to this issue. sys.stderr uses backslashreplace.Ok, fine.---+    _errno = errno;     Py_END_ALLOW_THREADS+    Py_XDECREF(bytes);     if (n < 0) {-        if (errno == EAGAIN)+        if (_errno == EAGAIN)             Py_RETURN_NONE;         PyErr_SetFromErrno(PyExc_IOError);---Hum, if you expect that _errno can be modified by Py_XDECREF(bytes), you must restore the previous errno value before calling PyErr_SetFromErrno(). This strategy is used inPython/fileutils.c.

New changeset2652c1798f7d by Victor Stinner in branch '3.4':Issue#25182: Fix compilation on Windowshttps://hg.python.org/cpython/rev/2652c1798f7dNew changeset0eb26a4d5ffa by Victor Stinner in branch '3.5':(Merge 3.4) Issue#25182: Fix compilation on Windowshttps://hg.python.org/cpython/rev/0eb26a4d5ffaNew changesetd1090d733d39 by Victor Stinner in branch 'default':(Merge 3.5) Issue#25182: Fix compilation on Windowshttps://hg.python.org/cpython/rev/d1090d733d39

Hum, the code didn't compile anymore on Windows. I took the opportunity to fix the errno issue that I saw.Note: In fact,Python/fileutils.c is a a little bit different. Functions like _Py_write() save errno to restore it later because the caller expects errno to be set.

> Hum, the code didn't compile anymore on Windows. I took the opportunity to> fix the errno issue that I saw.Thank you Victor.

> > This is not related to this issue. sys.stderr uses backslashreplace.> Ok, fine.But is related toissue25183.