From 871e6d6a9d1c453716f68e4e88268961d067b26d Mon Sep 17 00:00:00 2001
From: David Lord <davidism@gmail.com>
Date: Wed, 26 Jun 2019 14:32:20 -0700
Subject: [PATCH] don't clear BadRequestKeyError args

---
 CHANGES.rst       | 10 ++++++++++
 flask/__init__.py |  2 +-
 flask/app.py      | 10 +++++-----
 3 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/CHANGES.rst b/CHANGES.rst
index cd2cd09f..c92b384e 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -1,5 +1,15 @@
 .. currentmodule:: flask
 
+Version 1.0.4
+-------------
+
+Unreleased
+
+-   The key information for ``BadRequestKeyError`` is no longer cleared
+    outside debug mode, so error handlers can still access it. This
+    requires upgrading to Werkzeug 0.15.5. :issue:`3249`
+
+
 Version 1.0.3
 -------------
 
diff --git a/flask/__init__.py b/flask/__init__.py
index 1189e751..e514a8e1 100644
--- a/flask/__init__.py
+++ b/flask/__init__.py
@@ -10,7 +10,7 @@
     :license: BSD-3-Clause
 """
 
-__version__ = '1.0.3'
+__version__ = '1.0.4.dev'
 
 # utilities we import from Werkzeug and Jinja2 that are unused
 # in the module but are exported as public interface.
diff --git a/flask/app.py b/flask/app.py
index 0396865e..38fb7566 100644
--- a/flask/app.py
+++ b/flask/app.py
@@ -1724,14 +1724,14 @@ class Flask(_PackageBoundObject):
 
         if isinstance(e, BadRequestKeyError):
             if self.debug or self.config["TRAP_BAD_REQUEST_ERRORS"]:
+                e.show_exception = True
+
                 # Werkzeug < 0.15 doesn't add the KeyError to the 400
                 # message, add it in manually.
-                description = e.get_description()
-
-                if e.args[0] not in description:
+                # TODO: clean up once Werkzeug >= 0.15.5 is required
+                if e.args[0] not in e.get_description():
                     e.description = "KeyError: '{}'".format(*e.args)
-            else:
-                # Werkzeug >= 0.15 does add it, remove it in production
+            elif not hasattr(BadRequestKeyError, "show_exception"):
                 e.args = ()
 
         if isinstance(e, HTTPException) and not self.trap_http_exception(e):