From 5f256e241cfaaddb98ebfbdf9c75dde73012ed12 Mon Sep 17 00:00:00 2001
From: filipi87 <filipi87@gmail.com>
Date: Thu, 7 May 2026 11:29:57 -0300
Subject: [PATCH 1/2] Fixing a race condition when cleaning up the daily
 transport.

---
 src/pipecat/transports/daily/transport.py | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/pipecat/transports/daily/transport.py b/src/pipecat/transports/daily/transport.py
index 2d30ceecb..c4c76c0b0 100644
--- a/src/pipecat/transports/daily/transport.py
+++ b/src/pipecat/transports/daily/transport.py
@@ -526,6 +526,7 @@ class DailyTransportClient(EventHandler):
         self._joined = False
         self._joined_event = asyncio.Event()
         self._leave_counter = 0
+        self._cleanup_counter = 0
 
         self._task_manager: BaseTaskManager | None = None
 
@@ -741,6 +742,7 @@ class DailyTransportClient(EventHandler):
         Args:
             setup: The frame processor setup configuration.
         """
+        self._cleanup_counter += 1
         if self._task_manager:
             return
 
@@ -754,6 +756,12 @@ class DailyTransportClient(EventHandler):
 
     async def cleanup(self):
         """Cleanup client resources and cancel tasks."""
+        # Decrement cleanup counter. DailyInputTransport and DailyOutputTransport
+        # share this client and both call cleanup(), so only run on the last call.
+        self._cleanup_counter -= 1
+        if self._cleanup_counter > 0:
+            return
+
         if self._event_task and self._task_manager:
             await self._task_manager.cancel_task(self._event_task)
             self._event_task = None

From f91a55c97c2787dc19406ba7cb5438e4b5a01c93 Mon Sep 17 00:00:00 2001
From: filipi87 <filipi87@gmail.com>
Date: Thu, 7 May 2026 11:32:48 -0300
Subject: [PATCH 2/2] Changelog entry for the fix.

---
 changelog/4440.fixed.md | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 changelog/4440.fixed.md

diff --git a/changelog/4440.fixed.md b/changelog/4440.fixed.md
new file mode 100644
index 000000000..7be44d193
--- /dev/null
+++ b/changelog/4440.fixed.md
@@ -0,0 +1 @@
+- Fixed a race condition in the Daily transport that caused `AttributeError: 'NoneType' object has no attribute 'send_app_message'` when tearing down a pipeline. Both `DailyInputTransport` and `DailyOutputTransport` share the same `DailyTransportClient` and both call `cleanup()`, which was releasing the underlying `CallClient` on the first call — leaving the second caller with a `None` client.