Change PROPAGATE_EXCEPTIONS config default value to False

docs/config.rst

@@ -129,7 +129,10 @@ The following configuration values are used internally by Flask:
     handlers. If not set, this is implicitly true if ``TESTING`` or ``DEBUG``
     is enabled.
 
-    Default: ``None``
+    Default: ``False``
+
+    .. versionchanged:: 1.0
+        Default value is ``False`` now.
 
 .. py:data:: PRESERVE_CONTEXT_ON_EXCEPTION
 

flask/app.py

@@ -280,7 +280,7 @@ class Flask(_PackageBoundObject):
         'ENV':                                  None,
         'DEBUG':                                None,
         'TESTING':                              False,
-        'PROPAGATE_EXCEPTIONS':                 None,
+        'PROPAGATE_EXCEPTIONS':                 False,
         'PRESERVE_CONTEXT_ON_EXCEPTION':        None,
         'SECRET_KEY':                           None,
         'PERMANENT_SESSION_LIFETIME':           timedelta(days=31),

tests/test_basic.py

@@ -338,6 +338,8 @@ def test_session_using_session_settings(app, client):
 
 
 def test_session_using_samesite_attribute(app, client):
+    app.config['PROPAGATE_EXCEPTIONS'] = True
+
     @app.route('/')
     def index():
         flask.session['testing'] = 42
@@ -1027,6 +1029,8 @@ def test_errorhandler_precedence(app, client):
 
 
 def test_trapping_of_bad_request_key_errors(app, client):
+    app.config['PROPAGATE_EXCEPTIONS'] = True
+
     @app.route('/fail')
     def fail():
         flask.request.form['missing_key']
@@ -1045,6 +1049,7 @@ def test_trapping_of_bad_request_key_errors(app, client):
 
 
 def test_trapping_of_all_http_exceptions(app, client):
+    app.config['PROPAGATE_EXCEPTIONS'] = True
     app.config['TRAP_HTTP_EXCEPTIONS'] = True
 
     @app.route('/fail')
@@ -1085,6 +1090,7 @@ def test_error_handler_after_processor_error(app, client):
 
 def test_enctype_debug_helper(app, client):
     from flask.debughelpers import DebugFilesKeyError
+    app.config['PROPAGATE_EXCEPTIONS'] = True
     app.debug = True
 
     @app.route('/fail', methods=['POST'])
@@ -1180,6 +1186,7 @@ def test_response_types(app, client):
 
 def test_response_type_errors():
     app = flask.Flask(__name__)
+    app.config['PROPAGATE_EXCEPTIONS'] = True
     app.testing = True
 
     @app.route('/none')
@@ -1671,6 +1678,7 @@ def test_before_first_request_functions_concurrent(app, client):
 
 
 def test_routing_redirect_debugging(app, client):
+    app.config['PROPAGATE_EXCEPTIONS'] = True
     app.debug = True
 
     @app.route('/foo/', methods=['GET', 'POST'])
@@ -1719,6 +1727,7 @@ def test_route_decorator_custom_endpoint(app, client):
 
 
 def test_preserve_only_once(app, client):
+    app.config['PROPAGATE_EXCEPTIONS'] = True
     app.debug = True
 
     @app.route('/fail')
@@ -1738,6 +1747,7 @@ def test_preserve_only_once(app, client):
 
 
 def test_preserve_remembers_exception(app, client):
+    app.config['PROPAGATE_EXCEPTIONS'] = True
     app.debug = True
     errors = []
 

tests/test_templating.py

@@ -401,6 +401,7 @@ def test_templates_auto_reload_debug_run(app, monkeypatch):
 
 def test_template_loader_debugging(test_apps, monkeypatch):
     from blueprintapp import app
+    app.config['PROPAGATE_EXCEPTIONS'] = True
 
     called = []