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open() documentation still says default encoding is locale-dependent in 3.15 #148603
Description
Activity
open()now uses theUTF-8encoding by default, but it still uses the locale encoding if the UTF-8 Mode is disabled:$ LANG=fr_FR python3.15 -c 'print(open("/etc/issue").encoding)' utf-8 $ LANG=fr_FR python3.15 -X utf8=0 -c 'print(open("/etc/issue").encoding)' ISO-8859-1
- added a commit that references this issue
on Apr 15, 2026 Yep, label added.
- moved this from Todo to Done in Release and Deferred blockers 🚫
on Sep 15, 2026
Documentation
Documentation page
https://docs.python.org/3.15/library/functions.html#open
Bug description
The Python 3.15
open()documentation still says that the default encoding is platform-dependent and comes fromlocale.getencoding().But
What's New in Python 3.15says that Python 3.15 now uses UTF-8 as the default encoding for text files by default (PEP 686), independent of the system locale/environment:https://docs.python.org/3.15/whatsnew/3.15.html#whatsnew315-utf8-default
So these pages appear inconsistent and the
open()docs may still have pre-3.15 wording.Linked PRs
open()default encoding docs #148614