diff --git a/client/src/telethon/_impl/client/client/net.py b/client/src/telethon/_impl/client/client/net.py
index 075f21fb..84c8bff8 100644
--- a/client/src/telethon/_impl/client/client/net.py
+++ b/client/src/telethon/_impl/client/client/net.py
@@ -5,6 +5,7 @@ import itertools
 import logging
 import platform
 import re
+from asyncio import CancelledError
 from dataclasses import dataclass, field
 from typing import TYPE_CHECKING, Optional, TypeVar
 
@@ -272,6 +273,9 @@ async def step_sender(client: Client) -> None:
         else:
             # disconnect was called, so the socket returning 0 bytes is expected
             return
+    except CancelledError:
+        await disconnect(client)
+        return
 
     process_socket_updates(client, updates)
 
diff --git a/client/src/telethon/_impl/mtsender/sender.py b/client/src/telethon/_impl/mtsender/sender.py
index 0ef59f6a..792c1bd3 100644
--- a/client/src/telethon/_impl/mtsender/sender.py
+++ b/client/src/telethon/_impl/mtsender/sender.py
@@ -209,8 +209,9 @@ class Sender:
         )
 
     async def disconnect(self) -> None:
-        assert self._recv_task
-        assert self._send_task
+        if not self._recv_task or not self._send_task:
+            return
+
         recv_task, send_task = self._recv_task, self._send_task
 
         async with self._lock:
@@ -261,11 +262,10 @@ class Sender:
 
     async def _step(self) -> None:
         if self._step_counter == 0:
-            self._try_fill_write()
             self._recv_task = asyncio.create_task(self._do_recv())
             self._send_task = asyncio.create_task(self._do_send())
 
-        if self._recv_task is None or self._send_task is None:
+        if not self._recv_task or not self._send_task:
             # Disconnected
             return
 
@@ -300,9 +300,6 @@ class Sender:
             self._request_event.clear()
 
     def _try_fill_write(self) -> None:
-        if not self._requests:
-            return
-
         for request in self._requests:
             if isinstance(request.state, NotSerialized):
                 if (msg_id := self._mtp.push(request.body)) is not None: