diff --git a/src/paho/mqtt/client.py b/src/paho/mqtt/client.py
index 7bb10bef..76c601d7 100644
--- a/src/paho/mqtt/client.py
+++ b/src/paho/mqtt/client.py
@@ -34,7 +34,6 @@
 import urllib.parse
 import urllib.request
 import uuid
-import warnings
 from typing import TYPE_CHECKING, Any, Callable, Dict, Iterator, List, Sequence, Tuple, Union
 
 from .enums import ConnackCode, ConnectionState, LogLevel, MessageState, MessageType, MQTTErrorCode, MQTTProtocolVersion, PahoClientMode
@@ -783,11 +782,7 @@ def keepalive(self, value: int) -> None:
         if self._sock is not None:
             # The issue here is that the previous value of keepalive matter to possibly
             # sent ping packet.
-            warnings.warn(
-                "updating keepalive on established connection is not supported",
-                stacklevel=2,
-            )
-            self._sock.settimeout(value)
+            raise RuntimeError("updating keepalive on established connection is not supported")
 
         if value < 0:
             raise ValueError("Keepalive must be >=0.")
@@ -877,10 +872,7 @@ def max_inflight_messages(self, value: int) -> None:
         if self._sock is not None:
             # Not tested. Some doubt that everything is okay when max_inflight change between 0
             # and > 0 value because _update_inflight is skipped when _max_inflight_messages == 0
-            warnings.warn(
-                "updating max_inflight_messages on established connection is not supported",
-                stacklevel=2,
-            )
+            raise RuntimeError("updating max_inflight_messages on established connection is not supported")
 
         if value < 0:
             raise ValueError("Invalid inflight.")
@@ -897,10 +889,7 @@ def max_queued_messages(self, value: int) -> None:
         "Update max_queued_messages. It's behavior is undefined if the connection is already open"
         if self._sock is not None:
             # Not tested.
-            warnings.warn(
-                "updating max_queued_messages on established connection is not supported",
-                stacklevel=2,
-            )
+            raise RuntimeError("updating max_queued_messages on established connection is not supported")
 
         if value < 0:
             raise ValueError("Invalid queue size.")