diff --git a/slack_bolt/context/get_thread_context/async_get_thread_context.py b/slack_bolt/context/get_thread_context/async_get_thread_context.py
index cb8683a10..03f7c6076 100644
--- a/slack_bolt/context/get_thread_context/async_get_thread_context.py
+++ b/slack_bolt/context/get_thread_context/async_get_thread_context.py
@@ -31,14 +31,10 @@ async def __call__(self) -> Optional[AssistantThreadContext]:
         if self.thread_context_loaded is True:
             return self._thread_context
 
-        if self.payload.get("assistant_thread") is not None:
+        thread = self.payload.get("assistant_thread")
+        if isinstance(thread, dict) and thread.get("context", {}).get("channel_id") is not None:
             # assistant_thread_started
-            thread = self.payload["assistant_thread"]
-            self._thread_context = (
-                AssistantThreadContext(thread["context"])
-                if thread.get("context", {}).get("channel_id") is not None
-                else None
-            )
+            self._thread_context = AssistantThreadContext(thread["context"])
             # for this event, the context will never be changed
             self.thread_context_loaded = True
         elif self.payload.get("channel") is not None and self.payload.get("thread_ts") is not None:
diff --git a/slack_bolt/context/get_thread_context/get_thread_context.py b/slack_bolt/context/get_thread_context/get_thread_context.py
index 0a77d2d9f..b9c9751e1 100644
--- a/slack_bolt/context/get_thread_context/get_thread_context.py
+++ b/slack_bolt/context/get_thread_context/get_thread_context.py
@@ -31,14 +31,10 @@ def __call__(self) -> Optional[AssistantThreadContext]:
         if self.thread_context_loaded is True:
             return self._thread_context
 
-        if self.payload.get("assistant_thread") is not None:
+        thread = self.payload.get("assistant_thread")
+        if isinstance(thread, dict) and thread.get("context", {}).get("channel_id") is not None:
             # assistant_thread_started
-            thread = self.payload["assistant_thread"]
-            self._thread_context = (
-                AssistantThreadContext(thread["context"])
-                if thread.get("context", {}).get("channel_id") is not None
-                else None
-            )
+            self._thread_context = AssistantThreadContext(thread["context"])
             # for this event, the context will never be changed
             self.thread_context_loaded = True
         elif self.payload.get("channel") is not None and self.payload.get("thread_ts") is not None:
diff --git a/tests/scenario_tests/test_events_assistant.py b/tests/scenario_tests/test_events_assistant.py
index a970c9fa4..a1c3f1343 100644
--- a/tests/scenario_tests/test_events_assistant.py
+++ b/tests/scenario_tests/test_events_assistant.py
@@ -133,6 +133,12 @@ def handle_bot_message():
 
         app.assistant(assistant)
 
+        request = BoltRequest(body=user_message_event_body_with_action_token, mode="socket_mode")
+        response = app.dispatch(request)
+        assert response.status == 200
+        assert listener_called.wait(timeout=0.1) is True
+        listener_called.clear()
+
         request = BoltRequest(body=message_changed_event_body, mode="socket_mode")
         response = app.dispatch(request)
         assert response.status == 200
@@ -332,6 +338,25 @@ def build_payload(event: dict) -> dict:
     }
 )
 
+user_message_event_body_with_action_token = build_payload(
+    {
+        "user": "W222",
+        "type": "message",
+        "ts": "1726133700.887259",
+        "text": "When Slack was released?",
+        "team": "T111",
+        "user_team": "T111",
+        "source_team": "T222",
+        "user_profile": {},
+        "thread_ts": "1726133698.626339",
+        "parent_user_id": "W222",
+        "channel": "D111",
+        "event_ts": "1726133700.887259",
+        "channel_type": "im",
+        "assistant_thread": {"action_token": "10647138185092.960436384805.afce3599"},
+    }
+)
+
 message_changed_event_body = build_payload(
     {
         "type": "message",
diff --git a/tests/scenario_tests_async/test_events_assistant.py b/tests/scenario_tests_async/test_events_assistant.py
index 9b2e43eb1..9ccd80c11 100644
--- a/tests/scenario_tests_async/test_events_assistant.py
+++ b/tests/scenario_tests_async/test_events_assistant.py
@@ -157,6 +157,13 @@ async def handle_bot_message():
 
         app.assistant(assistant)
 
+        request = AsyncBoltRequest(body=user_message_event_body_with_action_token, mode="socket_mode")
+        response = await app.async_dispatch(request)
+        assert response.status == 200
+        await asyncio.sleep(0.1)
+        assert listener_called.is_set()
+        listener_called.clear()
+
         request = AsyncBoltRequest(body=message_changed_event_body, mode="socket_mode")
         response = await app.async_dispatch(request)
         assert response.status == 200
@@ -405,6 +412,25 @@ def build_payload(event: dict) -> dict:
 )
 
 
+user_message_event_body_with_action_token = build_payload(
+    {
+        "user": "W222",
+        "type": "message",
+        "ts": "1726133700.887259",
+        "text": "When Slack was released?",
+        "team": "T111",
+        "user_team": "T111",
+        "source_team": "T222",
+        "user_profile": {},
+        "thread_ts": "1726133698.626339",
+        "parent_user_id": "W222",
+        "channel": "D111",
+        "event_ts": "1726133700.887259",
+        "channel_type": "im",
+        "assistant_thread": {"action_token": "10647138185092.960436384805.afce3599"},
+    }
+)
+
 message_changed_event_body = build_payload(
     {
         "type": "message",