commit a9ba8ba9a71f3cb8d274c354ff67b6206abeb8ac
author Ethan Furman <ethan@stoneleaf.us> Wed Sep 16 17:37:51 2020 -0700
committer GitHub <noreply@github.com> Wed Sep 16 17:37:51 2020 -0700
tree 75d7cd7a6579d2f0b9ea4d510d142ad21709385d
parent 4465df626684fdc8eeb25ca248218cde2eeeb9ec

[3.9] bpo-39728: Enum: fix duplicate `ValueError` (GH-22277) (GH-22282)

fix default `_missing_` to return `None` instead of raising a `ValueError`
Co-authored-by: Andrey Darascheka <andrei.daraschenka@leverx.com>
(cherry picked from commit c95ad7a91fbd7636f33a098d3b39964ab083bf49)

Co-authored-by: Ethan Furman <ethan@stoneleaf.us>

Lib/enum.py

diff --git a/Lib/enum.py b/Lib/enum.py
index da5a31f..ebadd9f 100644
--- a/Lib/enum.py
+++ b/Lib/enum.py
@@ -628,7 +628,7 @@
 
     @classmethod
     def _missing_(cls, value):
-        raise ValueError("%r is not a valid %s" % (value, cls.__qualname__))
+        return None
 
     def __repr__(self):
         return "<%s.%s: %r>" % (