diff --git a/.readthedocs.yaml b/.readthedocs.yaml
index be8de8576..bf7948d41 100644
--- a/.readthedocs.yaml
+++ b/.readthedocs.yaml
@@ -15,4 +15,4 @@ build:
       - poetry config virtualenvs.create false
     post_install:
       # Install dependencies with 'docs' dependency group
-      - poetry install --with docs
+      - poetry install --with docs --all-extras
diff --git a/connexion/apps/abstract.py b/connexion/apps/abstract.py
index b2de31660..b54406498 100644
--- a/connexion/apps/abstract.py
+++ b/connexion/apps/abstract.py
@@ -23,7 +23,7 @@ class AbstractApp:
     interface, it delegates most of the work to the middleware and framework application.
     """
 
-    middleware_app: SpecMiddleware
+    _middleware_app: SpecMiddleware
     """
     The application wrapped by the ConnexionMiddleware, which in its turn wraps the framework
     application.
@@ -83,7 +83,7 @@ def __init__(
             :obj:`security.SECURITY_HANDLERS`
         """
         self.middleware = ConnexionMiddleware(
-            self.middleware_app,
+            self._middleware_app,
             import_name=import_name,
             lifespan=lifespan,
             middlewares=middlewares,
diff --git a/connexion/apps/asynchronous.py b/connexion/apps/asynchronous.py
index f2f93d0c5..a0702c0f5 100644
--- a/connexion/apps/asynchronous.py
+++ b/connexion/apps/asynchronous.py
@@ -171,7 +171,7 @@ def __init__(
         :param security_map: A dictionary of security handlers to use. Defaults to
             :obj:`security.SECURITY_HANDLERS`
         """
-        self.middleware_app: AsyncMiddlewareApp = AsyncMiddlewareApp()
+        self._middleware_app: AsyncMiddlewareApp = AsyncMiddlewareApp()
 
         super().__init__(
             import_name,
@@ -195,7 +195,7 @@ def __init__(
     def add_url_rule(
         self, rule, endpoint: str = None, view_func: t.Callable = None, **options
     ):
-        self.middleware_app.add_url_rule(
+        self._middleware_app.add_url_rule(
             rule, endpoint=endpoint, view_func=view_func, **options
         )
 
diff --git a/connexion/apps/flask.py b/connexion/apps/flask.py
index 946925676..5782218b1 100644
--- a/connexion/apps/flask.py
+++ b/connexion/apps/flask.py
@@ -171,7 +171,7 @@ async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
 class FlaskApp(AbstractApp):
     """Connexion Application based on ConnexionMiddleware wrapping a Flask application."""
 
-    middleware_app: FlaskMiddlewareApp
+    _middleware_app: FlaskMiddlewareApp
 
     def __init__(
         self,
@@ -231,8 +231,8 @@ def __init__(
         :param security_map: A dictionary of security handlers to use. Defaults to
             :obj:`security.SECURITY_HANDLERS`
         """
-        self.middleware_app = FlaskMiddlewareApp(import_name, server_args or {})
-        self.app = self.middleware_app.app
+        self._middleware_app = FlaskMiddlewareApp(import_name, server_args or {})
+        self.app = self._middleware_app.app
         super().__init__(
             import_name,
             lifespan=lifespan,
@@ -255,7 +255,7 @@ def __init__(
     def add_url_rule(
         self, rule, endpoint: str = None, view_func: t.Callable = None, **options
     ):
-        self.middleware_app.add_url_rule(
+        self._middleware_app.add_url_rule(
             rule, endpoint=endpoint, view_func=view_func, **options
         )