diff --git a/changelog.d/6271.misc b/changelog.d/6271.misc
new file mode 100644
index 000000000000..236976027281
--- /dev/null
+++ b/changelog.d/6271.misc
@@ -0,0 +1 @@
+Replace every instance of `logger.warn` method with `logger.warning` as the former is deprecated.
\ No newline at end of file
diff --git a/scripts/move_remote_media_to_new_store.py b/scripts/move_remote_media_to_new_store.py
index 12747c6024a0..b5b63933ab19 100755
--- a/scripts/move_remote_media_to_new_store.py
+++ b/scripts/move_remote_media_to_new_store.py
@@ -72,7 +72,7 @@ def move_media(origin_server, file_id, src_paths, dest_paths):
     # check that the original exists
     original_file = src_paths.remote_media_filepath(origin_server, file_id)
     if not os.path.exists(original_file):
-        logger.warn(
+        logger.warning(
             "Original for %s/%s (%s) does not exist",
             origin_server,
             file_id,
diff --git a/scripts/synapse_port_db b/scripts/synapse_port_db
index 54faed1e834f..0d3321682c6e 100755
--- a/scripts/synapse_port_db
+++ b/scripts/synapse_port_db
@@ -157,7 +157,7 @@ class Store(
                         )
                     except self.database_engine.module.DatabaseError as e:
                         if self.database_engine.is_deadlock(e):
-                            logger.warn("[TXN DEADLOCK] {%s} %d/%d", desc, i, N)
+                            logger.warning("[TXN DEADLOCK] {%s} %d/%d", desc, i, N)
                             if i < N:
                                 i += 1
                                 conn.rollback()
@@ -432,7 +432,7 @@ class Porter(object):
                     for row in rows:
                         d = dict(zip(headers, row))
                         if "\0" in d['value']:
-                            logger.warn('dropping search row %s', d)
+                            logger.warning('dropping search row %s', d)
                         else:
                             rows_dict.append(d)
 
@@ -647,7 +647,7 @@ class Porter(object):
             if isinstance(col, bytes):
                 return bytearray(col)
             elif isinstance(col, string_types) and "\0" in col:
-                logger.warn(
+                logger.warning(
                     "DROPPING ROW: NUL value in table %s col %s: %r",
                     table,
                     headers[j],
diff --git a/synapse/api/auth.py b/synapse/api/auth.py
index 53f3bb0fa8d6..5d0b7d2801eb 100644
--- a/synapse/api/auth.py
+++ b/synapse/api/auth.py
@@ -497,7 +497,7 @@ def get_appservice_by_req(self, request):
         token = self.get_access_token_from_request(request)
         service = self.store.get_app_service_by_token(token)
         if not service:
-            logger.warn("Unrecognised appservice access token.")
+            logger.warning("Unrecognised appservice access token.")
             raise InvalidClientTokenError()
         request.authenticated_entity = service.sender
         return defer.succeed(service)
diff --git a/synapse/app/__init__.py b/synapse/app/__init__.py
index d877c77834de..a01bac299789 100644
--- a/synapse/app/__init__.py
+++ b/synapse/app/__init__.py
@@ -44,6 +44,8 @@ def check_bind_error(e, address, bind_addresses):
         bind_addresses (list): Addresses on which the service listens.
     """
     if address == "0.0.0.0" and "::" in bind_addresses:
-        logger.warn("Failed to listen on 0.0.0.0, continuing because listening on [::]")
+        logger.warning(
+            "Failed to listen on 0.0.0.0, continuing because listening on [::]"
+        )
     else:
         raise e
diff --git a/synapse/app/appservice.py b/synapse/app/appservice.py
index 767b87d2db14..02b900f3826b 100644
--- a/synapse/app/appservice.py
+++ b/synapse/app/appservice.py
@@ -94,7 +94,7 @@ def start_listening(self, listeners):
                 )
             elif listener["type"] == "metrics":
                 if not self.get_config().enable_metrics:
-                    logger.warn(
+                    logger.warning(
                         (
                             "Metrics listener configured, but "
                             "enable_metrics is not True!"
@@ -103,7 +103,7 @@ def start_listening(self, listeners):
                 else:
                     _base.listen_metrics(listener["bind_addresses"], listener["port"])
             else:
-                logger.warn("Unrecognized listener type: %s", listener["type"])
+                logger.warning("Unrecognized listener type: %s", listener["type"])
 
         self.get_tcp_replication().start_replication(self)
 
diff --git a/synapse/app/client_reader.py b/synapse/app/client_reader.py
index dbcc414c424c..dadb487d5f44 100644
--- a/synapse/app/client_reader.py
+++ b/synapse/app/client_reader.py
@@ -153,7 +153,7 @@ def start_listening(self, listeners):
                 )
             elif listener["type"] == "metrics":
                 if not self.get_config().enable_metrics:
-                    logger.warn(
+                    logger.warning(
                         (
                             "Metrics listener configured, but "
                             "enable_metrics is not True!"
@@ -162,7 +162,7 @@ def start_listening(self, listeners):
                 else:
                     _base.listen_metrics(listener["bind_addresses"], listener["port"])
             else:
-                logger.warn("Unrecognized listener type: %s", listener["type"])
+                logger.warning("Unrecognized listener type: %s", listener["type"])
 
         self.get_tcp_replication().start_replication(self)
 
diff --git a/synapse/app/event_creator.py b/synapse/app/event_creator.py
index f20d810eceb6..d110599a3555 100644
--- a/synapse/app/event_creator.py
+++ b/synapse/app/event_creator.py
@@ -147,7 +147,7 @@ def start_listening(self, listeners):
                 )
             elif listener["type"] == "metrics":
                 if not self.get_config().enable_metrics:
-                    logger.warn(
+                    logger.warning(
                         (
                             "Metrics listener configured, but "
                             "enable_metrics is not True!"
@@ -156,7 +156,7 @@ def start_listening(self, listeners):
                 else:
                     _base.listen_metrics(listener["bind_addresses"], listener["port"])
             else:
-                logger.warn("Unrecognized listener type: %s", listener["type"])
+                logger.warning("Unrecognized listener type: %s", listener["type"])
 
         self.get_tcp_replication().start_replication(self)
 
diff --git a/synapse/app/federation_reader.py b/synapse/app/federation_reader.py
index 1ef027a88cb4..418c08625483 100644
--- a/synapse/app/federation_reader.py
+++ b/synapse/app/federation_reader.py
@@ -132,7 +132,7 @@ def start_listening(self, listeners):
                 )
             elif listener["type"] == "metrics":
                 if not self.get_config().enable_metrics:
-                    logger.warn(
+                    logger.warning(
                         (
                             "Metrics listener configured, but "
                             "enable_metrics is not True!"
@@ -141,7 +141,7 @@ def start_listening(self, listeners):
                 else:
                     _base.listen_metrics(listener["bind_addresses"], listener["port"])
             else:
-                logger.warn("Unrecognized listener type: %s", listener["type"])
+                logger.warning("Unrecognized listener type: %s", listener["type"])
 
         self.get_tcp_replication().start_replication(self)
 
diff --git a/synapse/app/federation_sender.py b/synapse/app/federation_sender.py
index 04fbb407af56..139221ad3457 100644
--- a/synapse/app/federation_sender.py
+++ b/synapse/app/federation_sender.py
@@ -123,7 +123,7 @@ def start_listening(self, listeners):
                 )
             elif listener["type"] == "metrics":
                 if not self.get_config().enable_metrics:
-                    logger.warn(
+                    logger.warning(
                         (
                             "Metrics listener configured, but "
                             "enable_metrics is not True!"
@@ -132,7 +132,7 @@ def start_listening(self, listeners):
                 else:
                     _base.listen_metrics(listener["bind_addresses"], listener["port"])
             else:
-                logger.warn("Unrecognized listener type: %s", listener["type"])
+                logger.warning("Unrecognized listener type: %s", listener["type"])
 
         self.get_tcp_replication().start_replication(self)
 
diff --git a/synapse/app/frontend_proxy.py b/synapse/app/frontend_proxy.py
index 9504bfbc70fb..e647459d0e2b 100644
--- a/synapse/app/frontend_proxy.py
+++ b/synapse/app/frontend_proxy.py
@@ -204,7 +204,7 @@ def start_listening(self, listeners):
                 )
             elif listener["type"] == "metrics":
                 if not self.get_config().enable_metrics:
-                    logger.warn(
+                    logger.warning(
                         (
                             "Metrics listener configured, but "
                             "enable_metrics is not True!"
@@ -213,7 +213,7 @@ def start_listening(self, listeners):
                 else:
                     _base.listen_metrics(listener["bind_addresses"], listener["port"])
             else:
-                logger.warn("Unrecognized listener type: %s", listener["type"])
+                logger.warning("Unrecognized listener type: %s", listener["type"])
 
         self.get_tcp_replication().start_replication(self)
 
diff --git a/synapse/app/homeserver.py b/synapse/app/homeserver.py
index eb54f5685347..8997c1f9e7ab 100644
--- a/synapse/app/homeserver.py
+++ b/synapse/app/homeserver.py
@@ -282,7 +282,7 @@ def start_listening(self, listeners):
                     reactor.addSystemEventTrigger("before", "shutdown", s.stopListening)
             elif listener["type"] == "metrics":
                 if not self.get_config().enable_metrics:
-                    logger.warn(
+                    logger.warning(
                         (
                             "Metrics listener configured, but "
                             "enable_metrics is not True!"
@@ -291,7 +291,7 @@ def start_listening(self, listeners):
                 else:
                     _base.listen_metrics(listener["bind_addresses"], listener["port"])
             else:
-                logger.warn("Unrecognized listener type: %s", listener["type"])
+                logger.warning("Unrecognized listener type: %s", listener["type"])
 
     def run_startup_checks(self, db_conn, database_engine):
         all_users_native = are_all_users_on_domain(
@@ -569,7 +569,7 @@ def phone_stats_home():
                 hs.config.report_stats_endpoint, stats
             )
         except Exception as e:
-            logger.warn("Error reporting stats: %s", e)
+            logger.warning("Error reporting stats: %s", e)
 
     def performance_stats_init():
         try:
diff --git a/synapse/app/media_repository.py b/synapse/app/media_repository.py
index 6bc7202f3306..2c6dd3ef025f 100644
--- a/synapse/app/media_repository.py
+++ b/synapse/app/media_repository.py
@@ -120,7 +120,7 @@ def start_listening(self, listeners):
                 )
             elif listener["type"] == "metrics":
                 if not self.get_config().enable_metrics:
-                    logger.warn(
+                    logger.warning(
                         (
                             "Metrics listener configured, but "
                             "enable_metrics is not True!"
@@ -129,7 +129,7 @@ def start_listening(self, listeners):
                 else:
                     _base.listen_metrics(listener["bind_addresses"], listener["port"])
             else:
-                logger.warn("Unrecognized listener type: %s", listener["type"])
+                logger.warning("Unrecognized listener type: %s", listener["type"])
 
         self.get_tcp_replication().start_replication(self)
 
diff --git a/synapse/app/pusher.py b/synapse/app/pusher.py
index d84732ee3ca1..01a5ffc36397 100644
--- a/synapse/app/pusher.py
+++ b/synapse/app/pusher.py
@@ -114,7 +114,7 @@ def start_listening(self, listeners):
                 )
             elif listener["type"] == "metrics":
                 if not self.get_config().enable_metrics:
-                    logger.warn(
+                    logger.warning(
                         (
                             "Metrics listener configured, but "
                             "enable_metrics is not True!"
@@ -123,7 +123,7 @@ def start_listening(self, listeners):
                 else:
                     _base.listen_metrics(listener["bind_addresses"], listener["port"])
             else:
-                logger.warn("Unrecognized listener type: %s", listener["type"])
+                logger.warning("Unrecognized listener type: %s", listener["type"])
 
         self.get_tcp_replication().start_replication(self)
 
diff --git a/synapse/app/synchrotron.py b/synapse/app/synchrotron.py
index 6a7e2fa70768..b14da09f47fb 100644
--- a/synapse/app/synchrotron.py
+++ b/synapse/app/synchrotron.py
@@ -326,7 +326,7 @@ def start_listening(self, listeners):
                 )
             elif listener["type"] == "metrics":
                 if not self.get_config().enable_metrics:
-                    logger.warn(
+                    logger.warning(
                         (
                             "Metrics listener configured, but "
                             "enable_metrics is not True!"
@@ -335,7 +335,7 @@ def start_listening(self, listeners):
                 else:
                     _base.listen_metrics(listener["bind_addresses"], listener["port"])
             else:
-                logger.warn("Unrecognized listener type: %s", listener["type"])
+                logger.warning("Unrecognized listener type: %s", listener["type"])
 
         self.get_tcp_replication().start_replication(self)
 
diff --git a/synapse/app/user_dir.py b/synapse/app/user_dir.py
index a5d6dc791572..6cb100319f25 100644
--- a/synapse/app/user_dir.py
+++ b/synapse/app/user_dir.py
@@ -150,7 +150,7 @@ def start_listening(self, listeners):
                 )
             elif listener["type"] == "metrics":
                 if not self.get_config().enable_metrics:
-                    logger.warn(
+                    logger.warning(
                         (
                             "Metrics listener configured, but "
                             "enable_metrics is not True!"
@@ -159,7 +159,7 @@ def start_listening(self, listeners):
                 else:
                     _base.listen_metrics(listener["bind_addresses"], listener["port"])
             else:
-                logger.warn("Unrecognized listener type: %s", listener["type"])
+                logger.warning("Unrecognized listener type: %s", listener["type"])
 
         self.get_tcp_replication().start_replication(self)
 
diff --git a/synapse/config/key.py b/synapse/config/key.py
index ec5d430afbb4..52ff1b26219a 100644
--- a/synapse/config/key.py
+++ b/synapse/config/key.py
@@ -125,7 +125,7 @@ def read_config(self, config, config_dir_path, **kwargs):
 
         # if neither trusted_key_servers nor perspectives are given, use the default.
         if "perspectives" not in config and "trusted_key_servers" not in config:
-            logger.warn(TRUSTED_KEY_SERVER_NOT_CONFIGURED_WARN)
+            logger.warning(TRUSTED_KEY_SERVER_NOT_CONFIGURED_WARN)
             key_servers = [{"server_name": "matrix.org"}]
         else:
             key_servers = config.get("trusted_key_servers", [])
@@ -156,7 +156,7 @@ def read_config(self, config, config_dir_path, **kwargs):
         if not self.macaroon_secret_key:
             # Unfortunately, there are people out there that don't have this
             # set. Lets just be "nice" and derive one from their secret key.
-            logger.warn("Config is missing macaroon_secret_key")
+            logger.warning("Config is missing macaroon_secret_key")
             seed = bytes(self.signing_key[0])
             self.macaroon_secret_key = hashlib.sha256(seed).digest()
 
diff --git a/synapse/config/logger.py b/synapse/config/logger.py
index be92e33f9332..2d2c1e54df6c 100644
--- a/synapse/config/logger.py
+++ b/synapse/config/logger.py
@@ -182,7 +182,7 @@ def _reload_stdlib_logging(*args, log_config=None):
     logger = logging.getLogger("")
 
     if not log_config:
-        logger.warn("Reloaded a blank config?")
+        logger.warning("Reloaded a blank config?")
 
     logging.config.dictConfig(log_config)
 
diff --git a/synapse/event_auth.py b/synapse/event_auth.py
index e7b722547b09..ec3243b27bee 100644
--- a/synapse/event_auth.py
+++ b/synapse/event_auth.py
@@ -77,7 +77,7 @@ def check(room_version, event, auth_events, do_sig_check=True, do_size_check=Tru
     if auth_events is None:
         # Oh, we don't know what the state of the room was, so we
         # are trusting that this is allowed (at least for now)
-        logger.warn("Trusting event: %s", event.event_id)
+        logger.warning("Trusting event: %s", event.event_id)
         return
 
     if event.type == EventTypes.Create:
diff --git a/synapse/federation/federation_base.py b/synapse/federation/federation_base.py
index 223aace0d960..0e22183280c6 100644
--- a/synapse/federation/federation_base.py
+++ b/synapse/federation/federation_base.py
@@ -102,7 +102,7 @@ def handle_check_result(pdu, deferred):
                     pass
 
             if not res:
-                logger.warn(
+                logger.warning(
                     "Failed to find copy of %s with valid signature", pdu.event_id
                 )
 
@@ -173,7 +173,7 @@ def callback(_, pdu):
                     return redacted_event
 
                 if self.spam_checker.check_event_for_spam(pdu):
-                    logger.warn(
+                    logger.warning(
                         "Event contains spam, redacting %s: %s",
                         pdu.event_id,
                         pdu.get_pdu_json(),
@@ -185,7 +185,7 @@ def callback(_, pdu):
         def errback(failure, pdu):
             failure.trap(SynapseError)
             with PreserveLoggingContext(ctx):
-                logger.warn(
+                logger.warning(
                     "Signature check failed for %s: %s",
                     pdu.event_id,
                     failure.getErrorMessage(),
diff --git a/synapse/federation/federation_client.py b/synapse/federation/federation_client.py
index f5c1632916f4..595706d01af1 100644
--- a/synapse/federation/federation_client.py
+++ b/synapse/federation/federation_client.py
@@ -522,12 +522,12 @@ def _try_destination_list(self, description, destinations, callback):
                 res = yield callback(destination)
                 return res
             except InvalidResponseError as e:
-                logger.warn("Failed to %s via %s: %s", description, destination, e)
+                logger.warning("Failed to %s via %s: %s", description, destination, e)
             except HttpResponseException as e:
                 if not 500 <= e.code < 600:
                     raise e.to_synapse_error()
                 else:
-                    logger.warn(
+                    logger.warning(
                         "Failed to %s via %s: %i %s",
                         description,
                         destination,
@@ -535,7 +535,9 @@ def _try_destination_list(self, description, destinations, callback):
                         e.args[0],
                     )
             except Exception:
-                logger.warn("Failed to %s via %s", description, destination, exc_info=1)
+                logger.warning(
+                    "Failed to %s via %s", description, destination, exc_info=1
+                )
 
         raise SynapseError(502, "Failed to %s via any server" % (description,))
 
diff --git a/synapse/federation/federation_server.py b/synapse/federation/federation_server.py
index d5a19764d2ee..d942d77a727b 100644
--- a/synapse/federation/federation_server.py
+++ b/synapse/federation/federation_server.py
@@ -220,7 +220,7 @@ async def process_pdus_for_room(room_id):
             try:
                 await self.check_server_matches_acl(origin_host, room_id)
             except AuthError as e:
-                logger.warn("Ignoring PDUs for room %s from banned server", room_id)
+                logger.warning("Ignoring PDUs for room %s from banned server", room_id)
                 for pdu in pdus_by_room[room_id]:
                     event_id = pdu.event_id
                     pdu_results[event_id] = e.error_dict()
@@ -233,7 +233,7 @@ async def process_pdus_for_room(room_id):
                         await self._handle_received_pdu(origin, pdu)
                         pdu_results[event_id] = {}
                     except FederationError as e:
-                        logger.warn("Error handling PDU %s: %s", event_id, e)
+                        logger.warning("Error handling PDU %s: %s", event_id, e)
                         pdu_results[event_id] = {"error": str(e)}
                     except Exception as e:
                         f = failure.Failure()
@@ -333,7 +333,9 @@ async def on_make_join_request(self, origin, room_id, user_id, supported_version
 
         room_version = await self.store.get_room_version(room_id)
         if room_version not in supported_versions:
-            logger.warn("Room version %s not in %s", room_version, supported_versions)
+            logger.warning(
+                "Room version %s not in %s", room_version, supported_versions
+            )
             raise IncompatibleRoomVersionError(room_version=room_version)
 
         pdu = await self.handler.on_make_join_request(origin, room_id, user_id)
@@ -679,7 +681,7 @@ def server_matches_acl_event(server_name, acl_event):
     # server name is a literal IP
     allow_ip_literals = acl_event.content.get("allow_ip_literals", True)
     if not isinstance(allow_ip_literals, bool):
-        logger.warn("Ignorning non-bool allow_ip_literals flag")
+        logger.warning("Ignorning non-bool allow_ip_literals flag")
         allow_ip_literals = True
     if not allow_ip_literals:
         # check for ipv6 literals. These start with '['.
@@ -693,7 +695,7 @@ def server_matches_acl_event(server_name, acl_event):
     # next,  check the deny list
     deny = acl_event.content.get("deny", [])
     if not isinstance(deny, (list, tuple)):
-        logger.warn("Ignorning non-list deny ACL %s", deny)
+        logger.warning("Ignorning non-list deny ACL %s", deny)
         deny = []
     for e in deny:
         if _acl_entry_matches(server_name, e):
@@ -703,7 +705,7 @@ def server_matches_acl_event(server_name, acl_event):
     # then the allow list.
     allow = acl_event.content.get("allow", [])
     if not isinstance(allow, (list, tuple)):
-        logger.warn("Ignorning non-list allow ACL %s", allow)
+        logger.warning("Ignorning non-list allow ACL %s", allow)
         allow = []
     for e in allow:
         if _acl_entry_matches(server_name, e):
@@ -717,7 +719,7 @@ def server_matches_acl_event(server_name, acl_event):
 
 def _acl_entry_matches(server_name, acl_entry):
     if not isinstance(acl_entry, six.string_types):
-        logger.warn(
+        logger.warning(
             "Ignoring non-str ACL entry '%s' (is %s)", acl_entry, type(acl_entry)
         )
         return False
@@ -772,7 +774,7 @@ def register_query_handler(self, query_type, handler):
     async def on_edu(self, edu_type, origin, content):
         handler = self.edu_handlers.get(edu_type)
         if not handler:
-            logger.warn("No handler registered for EDU type %s", edu_type)
+            logger.warning("No handler registered for EDU type %s", edu_type)
 
         with start_active_span_from_edu(content, "handle_edu"):
             try:
@@ -785,7 +787,7 @@ async def on_edu(self, edu_type, origin, content):
     def on_query(self, query_type, args):
         handler = self.query_handlers.get(query_type)
         if not handler:
-            logger.warn("No handler registered for query type %s", query_type)
+            logger.warning("No handler registered for query type %s", query_type)
             raise NotFoundError("No handler for Query type '%s'" % (query_type,))
 
         return handler(args)
diff --git a/synapse/federation/sender/transaction_manager.py b/synapse/federation/sender/transaction_manager.py
index 5b6c79c51afd..67b3e1ab6e53 100644
--- a/synapse/federation/sender/transaction_manager.py
+++ b/synapse/federation/sender/transaction_manager.py
@@ -146,7 +146,7 @@ def json_data_cb():
             if code == 200:
                 for e_id, r in response.get("pdus", {}).items():
                     if "error" in r:
-                        logger.warn(
+                        logger.warning(
                             "TX [%s] {%s} Remote returned error for %s: %s",
                             destination,
                             txn_id,
@@ -155,7 +155,7 @@ def json_data_cb():
                         )
             else:
                 for p in pdus:
-                    logger.warn(
+                    logger.warning(
                         "TX [%s] {%s} Failed to send event %s",
                         destination,
                         txn_id,
diff --git a/synapse/federation/transport/server.py b/synapse/federation/transport/server.py
index 0f16f21c2d8b..d6c23f22bd9a 100644
--- a/synapse/federation/transport/server.py
+++ b/synapse/federation/transport/server.py
@@ -202,7 +202,7 @@ def strip_quotes(value):
         sig = strip_quotes(param_dict["sig"])
         return origin, key, sig
     except Exception as e:
-        logger.warn(
+        logger.warning(
             "Error parsing auth header '%s': %s",
             header_bytes.decode("ascii", "replace"),
             e,
@@ -287,10 +287,12 @@ async def new_func(request, *args, **kwargs):
             except NoAuthenticationError:
                 origin = None
                 if self.REQUIRE_AUTH:
-                    logger.warn("authenticate_request failed: missing authentication")
+                    logger.warning(
+                        "authenticate_request failed: missing authentication"
+                    )
                     raise
             except Exception as e:
-                logger.warn("authenticate_request failed: %s", e)
+                logger.warning("authenticate_request failed: %s", e)
                 raise
 
             request_tags = {
diff --git a/synapse/groups/attestations.py b/synapse/groups/attestations.py
index dfd7ae041ba6..d950a8b246d9 100644
--- a/synapse/groups/attestations.py
+++ b/synapse/groups/attestations.py
@@ -181,7 +181,7 @@ def _renew_attestation(group_id, user_id):
                 elif not self.is_mine_id(user_id):
                     destination = get_domain_from_id(user_id)
                 else:
-                    logger.warn(
+                    logger.warning(
                         "Incorrectly trying to do attestations for user: %r in %r",
                         user_id,
                         group_id,
diff --git a/synapse/groups/groups_server.py b/synapse/groups/groups_server.py
index 8f10b6adbb03..29e8ffc295f2 100644
--- a/synapse/groups/groups_server.py
+++ b/synapse/groups/groups_server.py
@@ -488,7 +488,7 @@ def get_invited_users_in_group(self, group_id, requester_user_id):
                 profile = yield self.profile_handler.get_profile_from_cache(user_id)
                 user_profile.update(profile)
             except Exception as e:
-                logger.warn("Error getting profile for %s: %s", user_id, e)
+                logger.warning("Error getting profile for %s: %s", user_id, e)
             user_profiles.append(user_profile)
 
         return {"chunk": user_profiles, "total_user_count_estimate": len(invited_users)}
diff --git a/synapse/handlers/auth.py b/synapse/handlers/auth.py
index 333eb30625af..7a0f54ca244d 100644
--- a/synapse/handlers/auth.py
+++ b/synapse/handlers/auth.py
@@ -525,7 +525,7 @@ def _find_user_id_and_pwd_hash(self, user_id):
 
         result = None
         if not user_infos:
-            logger.warn("Attempted to login as %s but they do not exist", user_id)
+            logger.warning("Attempted to login as %s but they do not exist", user_id)
         elif len(user_infos) == 1:
             # a single match (possibly not exact)
             result = user_infos.popitem()
@@ -534,7 +534,7 @@ def _find_user_id_and_pwd_hash(self, user_id):
             result = (user_id, user_infos[user_id])
         else:
             # multiple matches, none of them exact
-            logger.warn(
+            logger.warning(
                 "Attempted to login as %s but it matches more than one user "
                 "inexactly: %r",
                 user_id,
@@ -728,7 +728,7 @@ def _check_local_password(self, user_id, password):
 
         result = yield self.validate_hash(password, password_hash)
         if not result:
-            logger.warn("Failed password login for user %s", user_id)
+            logger.warning("Failed password login for user %s", user_id)
             return None
         return user_id
 
diff --git a/synapse/handlers/device.py b/synapse/handlers/device.py
index 5f23ee448876..befef2cf3ddd 100644
--- a/synapse/handlers/device.py
+++ b/synapse/handlers/device.py
@@ -656,7 +656,7 @@ def user_device_resync(self, user_id):
         except (NotRetryingDestination, RequestSendFailed, HttpResponseException):
             # TODO: Remember that we are now out of sync and try again
             # later
-            logger.warn("Failed to handle device list update for %s", user_id)
+            logger.warning("Failed to handle device list update for %s", user_id)
             # We abort on exceptions rather than accepting the update
             # as otherwise synapse will 'forget' that its device list
             # is out of date. If we bail then we will retry the resync
@@ -694,7 +694,7 @@ def user_device_resync(self, user_id):
         # up on storing the total list of devices and only handle the
         # delta instead.
         if len(devices) > 1000:
-            logger.warn(
+            logger.warning(
                 "Ignoring device list snapshot for %s as it has >1K devs (%d)",
                 user_id,
                 len(devices),
diff --git a/synapse/handlers/devicemessage.py b/synapse/handlers/devicemessage.py
index 0043cbea17da..73b9e120f5bb 100644
--- a/synapse/handlers/devicemessage.py
+++ b/synapse/handlers/devicemessage.py
@@ -52,7 +52,7 @@ def on_direct_to_device_edu(self, origin, content):
         local_messages = {}
         sender_user_id = content["sender"]
         if origin != get_domain_from_id(sender_user_id):
-            logger.warn(
+            logger.warning(
                 "Dropping device message from %r with spoofed sender %r",
                 origin,
                 sender_user_id,
diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py
index 08276fdebf46..f1547e303989 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -181,7 +181,7 @@ def on_receive_pdu(self, origin, pdu, sent_to_us_directly=False):
         try:
             self._sanity_check_event(pdu)
         except SynapseError as err:
-            logger.warn(
+            logger.warning(
                 "[%s %s] Received event failed sanity checks", room_id, event_id
             )
             raise FederationError("ERROR", err.code, err.msg, affected=pdu.event_id)
@@ -302,7 +302,7 @@ def on_receive_pdu(self, origin, pdu, sent_to_us_directly=False):
                 # following.
 
                 if sent_to_us_directly:
-                    logger.warn(
+                    logger.warning(
                         "[%s %s] Rejecting: failed to fetch %d prev events: %s",
                         room_id,
                         event_id,
@@ -406,7 +406,7 @@ def on_receive_pdu(self, origin, pdu, sent_to_us_directly=False):
                     state = [event_map[e] for e in six.itervalues(state_map)]
                     auth_chain = list(auth_chains)
                 except Exception:
-                    logger.warn(
+                    logger.warning(
                         "[%s %s] Error attempting to resolve state at missing "
                         "prev_events",
                         room_id,
@@ -519,7 +519,9 @@ def _get_missing_events_for_pdu(self, origin, pdu, prevs, min_depth):
             # We failed to get the missing events, but since we need to handle
             # the case of `get_missing_events` not returning the necessary
             # events anyway, it is safe to simply log the error and continue.
-            logger.warn("[%s %s]: Failed to get prev_events: %s", room_id, event_id, e)
+            logger.warning(
+                "[%s %s]: Failed to get prev_events: %s", room_id, event_id, e
+            )
             return
 
         logger.info(
@@ -546,7 +548,7 @@ def _get_missing_events_for_pdu(self, origin, pdu, prevs, min_depth):
                     yield self.on_receive_pdu(origin, ev, sent_to_us_directly=False)
                 except FederationError as e:
                     if e.code == 403:
-                        logger.warn(
+                        logger.warning(
                             "[%s %s] Received prev_event %s failed history check.",
                             room_id,
                             event_id,
@@ -1060,7 +1062,7 @@ def _sanity_check_event(self, ev):
             SynapseError if the event does not pass muster
         """
         if len(ev.prev_event_ids()) > 20:
-            logger.warn(
+            logger.warning(
                 "Rejecting event %s which has %i prev_events",
                 ev.event_id,
                 len(ev.prev_event_ids()),
@@ -1068,7 +1070,7 @@ def _sanity_check_event(self, ev):
             raise SynapseError(http_client.BAD_REQUEST, "Too many prev_events")
 
         if len(ev.auth_event_ids()) > 10:
-            logger.warn(
+            logger.warning(
                 "Rejecting event %s which has %i auth_events",
                 ev.event_id,
                 len(ev.auth_event_ids()),
@@ -1204,7 +1206,7 @@ def _handle_queued_pdus(self, room_queue):
                 with nested_logging_context(p.event_id):
                     yield self.on_receive_pdu(origin, p, sent_to_us_directly=True)
             except Exception as e:
-                logger.warn(
+                logger.warning(
                     "Error handling queued PDU %s from %s: %s", p.event_id, origin, e
                 )
 
@@ -1251,7 +1253,7 @@ def on_make_join_request(self, origin, room_id, user_id):
                 builder=builder
             )
         except AuthError as e:
-            logger.warn("Failed to create join to %s because %s", room_id, e)
+            logger.warning("Failed to create join to %s because %s", room_id, e)
             raise e
 
         event_allowed = yield self.third_party_event_rules.check_event_allowed(
@@ -1495,7 +1497,7 @@ def on_make_leave_request(self, origin, room_id, user_id):
                 room_version, event, context, do_sig_check=False
             )
         except AuthError as e:
-            logger.warn("Failed to create new leave %r because %s", event, e)
+            logger.warning("Failed to create new leave %r because %s", event, e)
             raise e
 
         return event
@@ -1789,7 +1791,7 @@ def _persist_auth_tree(self, origin, auth_events, state, event):
                 # cause SynapseErrors in auth.check. We don't want to give up
                 # the attempt to federate altogether in such cases.
 
-                logger.warn("Rejecting %s because %s", e.event_id, err.msg)
+                logger.warning("Rejecting %s because %s", e.event_id, err.msg)
 
                 if e == event:
                     raise
@@ -1845,7 +1847,9 @@ def _prep_event(self, origin, event, state, auth_events, backfilled):
         try:
             yield self.do_auth(origin, event, context, auth_events=auth_events)
         except AuthError as e:
-            logger.warn("[%s %s] Rejecting: %s", event.room_id, event.event_id, e.msg)
+            logger.warning(
+                "[%s %s] Rejecting: %s", event.room_id, event.event_id, e.msg
+            )
 
             context.rejected = RejectedReason.AUTH_ERROR
 
@@ -1939,7 +1943,7 @@ def _check_for_soft_fail(self, event, state, backfilled):
             try:
                 event_auth.check(room_version, event, auth_events=current_auth_events)
             except AuthError as e:
-                logger.warn("Soft-failing %r because %s", event, e)
+                logger.warning("Soft-failing %r because %s", event, e)
                 event.internal_metadata.soft_failed = True
 
     @defer.inlineCallbacks
@@ -2038,7 +2042,7 @@ def do_auth(self, origin, event, context, auth_events):
         try:
             event_auth.check(room_version, event, auth_events=auth_events)
         except AuthError as e:
-            logger.warn("Failed auth resolution for %r because %s", event, e)
+            logger.warning("Failed auth resolution for %r because %s", event, e)
             raise e
 
     @defer.inlineCallbacks
@@ -2432,7 +2436,7 @@ def exchange_third_party_invite(
             try:
                 yield self.auth.check_from_context(room_version, event, context)
             except AuthError as e:
-                logger.warn("Denying new third party invite %r because %s", event, e)
+                logger.warning("Denying new third party invite %r because %s", event, e)
                 raise e
 
             yield self._check_signature(event, context)
@@ -2488,7 +2492,7 @@ def on_exchange_third_party_invite_request(self, room_id, event_dict):
         try:
             yield self.auth.check_from_context(room_version, event, context)
         except AuthError as e:
-            logger.warn("Denying third party invite %r because %s", event, e)
+            logger.warning("Denying third party invite %r because %s", event, e)
             raise e
         yield self._check_signature(event, context)
 
diff --git a/synapse/handlers/groups_local.py b/synapse/handlers/groups_local.py
index 46eb9ee88b53..92fecbfc44aa 100644
--- a/synapse/handlers/groups_local.py
+++ b/synapse/handlers/groups_local.py
@@ -392,7 +392,7 @@ def on_invite(self, group_id, user_id, content):
         try:
             user_profile = yield self.profile_handler.get_profile(user_id)
         except Exception as e:
-            logger.warn("No profile for user %s: %s", user_id, e)
+            logger.warning("No profile for user %s: %s", user_id, e)
             user_profile = {}
 
         return {"state": "invite", "user_profile": user_profile}
diff --git a/synapse/handlers/identity.py b/synapse/handlers/identity.py
index ba99ddf76dbd..000fbf090f83 100644
--- a/synapse/handlers/identity.py
+++ b/synapse/handlers/identity.py
@@ -272,7 +272,7 @@ def try_unbind_threepid_with_id_server(self, mxid, threepid, id_server):
             changed = False
             if e.code in (400, 404, 501):
                 # The remote server probably doesn't support unbinding (yet)
-                logger.warn("Received %d response while unbinding threepid", e.code)
+                logger.warning("Received %d response while unbinding threepid", e.code)
             else:
                 logger.error("Failed to unbind threepid on identity server: %s", e)
                 raise SynapseError(500, "Failed to contact identity server")
@@ -403,7 +403,7 @@ def requestEmailToken(
 
         if self.hs.config.using_identity_server_from_trusted_list:
             # Warn that a deprecated config option is in use
-            logger.warn(
+            logger.warning(
                 'The config option "trust_identity_server_for_password_resets" '
                 'has been replaced by "account_threepid_delegate". '
                 "Please consult the sample config at docs/sample_config.yaml for "
@@ -457,7 +457,7 @@ def requestMsisdnToken(
 
         if self.hs.config.using_identity_server_from_trusted_list:
             # Warn that a deprecated config option is in use
-            logger.warn(
+            logger.warning(
                 'The config option "trust_identity_server_for_password_resets" '
                 'has been replaced by "account_threepid_delegate". '
                 "Please consult the sample config at docs/sample_config.yaml for "
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index 7908a2d52c8e..5698e5fee03d 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -688,7 +688,7 @@ def handle_new_client_event(
         try:
             yield self.auth.check_from_context(room_version, event, context)
         except AuthError as err:
-            logger.warn("Denying new event %r because %s", event, err)
+            logger.warning("Denying new event %r because %s", event, err)
             raise err
 
         # Ensure that we can round trip before trying to persist in db
diff --git a/synapse/handlers/profile.py b/synapse/handlers/profile.py
index 8690f69d4549..22e0a04da46b 100644
--- a/synapse/handlers/profile.py
+++ b/synapse/handlers/profile.py
@@ -275,7 +275,7 @@ def _update_join_states(self, requester, target_user):
                     ratelimit=False,  # Try to hide that these events aren't atomic.
                 )
             except Exception as e:
-                logger.warn(
+                logger.warning(
                     "Failed to update join event for room %s - %s", room_id, str(e)
                 )
 
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py
index 2816bd8f8731..445a08f445f2 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -922,7 +922,7 @@ def get_new_events(
 
         from_token = RoomStreamToken.parse(from_key)
         if from_token.topological:
-            logger.warn("Stream has topological part!!!! %r", from_key)
+            logger.warning("Stream has topological part!!!! %r", from_key)
             from_key = "s%s" % (from_token.stream,)
 
         app_service = self.store.get_app_service_by_user_id(user.to_string())
diff --git a/synapse/http/client.py b/synapse/http/client.py
index cdf828a4ff44..2df5b383b5d2 100644
--- a/synapse/http/client.py
+++ b/synapse/http/client.py
@@ -535,7 +535,7 @@ def get_file(self, url, output_stream, max_size=None, headers=None):
             b"Content-Length" in resp_headers
             and int(resp_headers[b"Content-Length"][0]) > max_size
         ):
-            logger.warn("Requested URL is too large > %r bytes" % (self.max_size,))
+            logger.warning("Requested URL is too large > %r bytes" % (self.max_size,))
             raise SynapseError(
                 502,
                 "Requested file is too large > %r bytes" % (self.max_size,),
@@ -543,7 +543,7 @@ def get_file(self, url, output_stream, max_size=None, headers=None):
             )
 
         if response.code > 299:
-            logger.warn("Got %d when downloading %s" % (response.code, url))
+            logger.warning("Got %d when downloading %s" % (response.code, url))
             raise SynapseError(502, "Got error %d" % (response.code,), Codes.UNKNOWN)
 
         # TODO: if our Content-Type is HTML or something, just read the first
diff --git a/synapse/http/federation/srv_resolver.py b/synapse/http/federation/srv_resolver.py
index 3fe4ffb9e5f4..021b233a7d9d 100644
--- a/synapse/http/federation/srv_resolver.py
+++ b/synapse/http/federation/srv_resolver.py
@@ -148,7 +148,7 @@ def resolve_service(self, service_name):
             # Try something in the cache, else rereaise
             cache_entry = self._cache.get(service_name, None)
             if cache_entry:
-                logger.warn(
+                logger.warning(
                     "Failed to resolve %r, falling back to cache. %r", service_name, e
                 )
                 return list(cache_entry)
diff --git a/synapse/http/matrixfederationclient.py b/synapse/http/matrixfederationclient.py
index 3f7c93ffcbfc..691380abda9d 100644
--- a/synapse/http/matrixfederationclient.py
+++ b/synapse/http/matrixfederationclient.py
@@ -149,7 +149,7 @@ def _handle_json_response(reactor, timeout_sec, request, response):
 
         body = yield make_deferred_yieldable(d)
     except Exception as e:
-        logger.warn(
+        logger.warning(
             "{%s} [%s] Error reading response: %s",
             request.txn_id,
             request.destination,
@@ -457,7 +457,7 @@ def _send_request(
                         except Exception as e:
                             # Eh, we're already going to raise an exception so lets
                             # ignore if this fails.
-                            logger.warn(
+                            logger.warning(
                                 "{%s} [%s] Failed to get error response: %s %s: %s",
                                 request.txn_id,
                                 request.destination,
@@ -478,7 +478,7 @@ def _send_request(
 
                     break
                 except RequestSendFailed as e:
-                    logger.warn(
+                    logger.warning(
                         "{%s} [%s] Request failed: %s %s: %s",
                         request.txn_id,
                         request.destination,
@@ -513,7 +513,7 @@ def _send_request(
                         raise
 
                 except Exception as e:
-                    logger.warn(
+                    logger.warning(
                         "{%s} [%s] Request failed: %s %s: %s",
                         request.txn_id,
                         request.destination,
@@ -889,7 +889,7 @@ def get_file(
             d.addTimeout(self.default_timeout, self.reactor)
             length = yield make_deferred_yieldable(d)
         except Exception as e:
-            logger.warn(
+            logger.warning(
                 "{%s} [%s] Error reading response: %s",
                 request.txn_id,
                 request.destination,
diff --git a/synapse/http/request_metrics.py b/synapse/http/request_metrics.py
index 46af27c8f651..58f9cc61c825 100644
--- a/synapse/http/request_metrics.py
+++ b/synapse/http/request_metrics.py
@@ -170,7 +170,7 @@ def stop(self, time_sec, response_code, sent_bytes):
             tag = context.tag
 
             if context != self.start_context:
-                logger.warn(
+                logger.warning(
                     "Context have unexpectedly changed %r, %r",
                     context,
                     self.start_context,
diff --git a/synapse/http/server.py b/synapse/http/server.py
index 2ccb210fd651..943d12c90742 100644
--- a/synapse/http/server.py
+++ b/synapse/http/server.py
@@ -454,7 +454,7 @@ def respond_with_json(
     # the Deferred fires, but since the flag is RIGHT THERE it seems like
     # a waste.
     if request._disconnected:
-        logger.warn(
+        logger.warning(
             "Not sending response to request %s, already disconnected.", request
         )
         return
diff --git a/synapse/http/servlet.py b/synapse/http/servlet.py
index 274c1a6a879b..e9a5e46ced27 100644
--- a/synapse/http/servlet.py
+++ b/synapse/http/servlet.py
@@ -219,13 +219,13 @@ def parse_json_value_from_request(request, allow_empty_body=False):
     try:
         content_unicode = content_bytes.decode("utf8")
     except UnicodeDecodeError:
-        logger.warn("Unable to decode UTF-8")
+        logger.warning("Unable to decode UTF-8")
         raise SynapseError(400, "Content not JSON.", errcode=Codes.NOT_JSON)
 
     try:
         content = json.loads(content_unicode)
     except Exception as e:
-        logger.warn("Unable to parse JSON: %s", e)
+        logger.warning("Unable to parse JSON: %s", e)
         raise SynapseError(400, "Content not JSON.", errcode=Codes.NOT_JSON)
 
     return content
diff --git a/synapse/http/site.py b/synapse/http/site.py
index df5274c17766..ff8184a3d0be 100644
--- a/synapse/http/site.py
+++ b/synapse/http/site.py
@@ -199,7 +199,7 @@ def connectionLost(self, reason):
         # It's useful to log it here so that we can get an idea of when
         # the client disconnects.
         with PreserveLoggingContext(self.logcontext):
-            logger.warn(
+            logger.warning(
                 "Error processing request %r: %s %s", self, reason.type, reason.value
             )
 
@@ -305,7 +305,7 @@ def _finished_processing(self):
         try:
             self.request_metrics.stop(self.finish_time, self.code, self.sentLength)
         except Exception as e:
-            logger.warn("Failed to stop metrics: %r", e)
+            logger.warning("Failed to stop metrics: %r", e)
 
 
 class XForwardedForRequest(SynapseRequest):
diff --git a/synapse/logging/context.py b/synapse/logging/context.py
index 370000e377ae..2c1fb9ddacba 100644
--- a/synapse/logging/context.py
+++ b/synapse/logging/context.py
@@ -294,7 +294,7 @@ def __enter__(self):
         """Enters this logging context into thread local storage"""
         old_context = self.set_current_context(self)
         if self.previous_context != old_context:
-            logger.warn(
+            logger.warning(
                 "Expected previous context %r, found %r",
                 self.previous_context,
                 old_context,
diff --git a/synapse/push/httppusher.py b/synapse/push/httppusher.py
index 629958780829..23d367842001 100644
--- a/synapse/push/httppusher.py
+++ b/synapse/push/httppusher.py
@@ -246,7 +246,7 @@ def _unsafe_process(self):
                     # we really only give up so that if the URL gets
                     # fixed, we don't suddenly deliver a load
                     # of old notifications.
-                    logger.warn(
+                    logger.warning(
                         "Giving up on a notification to user %s, " "pushkey %s",
                         self.user_id,
                         self.pushkey,
@@ -299,7 +299,7 @@ def _process_one(self, push_action):
                 if pk != self.pushkey:
                     # for sanity, we only remove the pushkey if it
                     # was the one we actually sent...
-                    logger.warn(
+                    logger.warning(
                         ("Ignoring rejected pushkey %s because we" " didn't send it"),
                         pk,
                     )
diff --git a/synapse/push/push_rule_evaluator.py b/synapse/push/push_rule_evaluator.py
index 5ed9147de4da..b1587183a8e7 100644
--- a/synapse/push/push_rule_evaluator.py
+++ b/synapse/push/push_rule_evaluator.py
@@ -117,7 +117,7 @@ def _event_match(self, condition, user_id):
                 pattern = UserID.from_string(user_id).localpart
 
         if not pattern:
-            logger.warn("event_match condition with no pattern")
+            logger.warning("event_match condition with no pattern")
             return False
 
         # XXX: optimisation: cache our pattern regexps
@@ -173,7 +173,7 @@ def _glob_matches(glob, value, word_boundary=False):
             regex_cache[(glob, word_boundary)] = r
         return r.search(value)
     except re.error:
-        logger.warn("Failed to parse glob to regex: %r", glob)
+        logger.warning("Failed to parse glob to regex: %r", glob)
         return False
 
 
diff --git a/synapse/replication/http/_base.py b/synapse/replication/http/_base.py
index 9be37cd99802..c8056b0c0c97 100644
--- a/synapse/replication/http/_base.py
+++ b/synapse/replication/http/_base.py
@@ -180,7 +180,7 @@ def send_request(**kwargs):
                         if e.code != 504 or not cls.RETRY_ON_TIMEOUT:
                             raise
 
-                    logger.warn("%s request timed out", cls.NAME)
+                    logger.warning("%s request timed out", cls.NAME)
 
                     # If we timed out we probably don't need to worry about backing
                     # off too much, but lets just wait a little anyway.
diff --git a/synapse/replication/http/membership.py b/synapse/replication/http/membership.py
index b5f5f13a62a5..cc1f2497401e 100644
--- a/synapse/replication/http/membership.py
+++ b/synapse/replication/http/membership.py
@@ -144,7 +144,7 @@ async def _handle_request(self, request, room_id, user_id):
             # The 'except' clause is very broad, but we need to
             # capture everything from DNS failures upwards
             #
-            logger.warn("Failed to reject invite: %s", e)
+            logger.warning("Failed to reject invite: %s", e)
 
             await self.store.locally_reject_invite(user_id, room_id)
             ret = {}
diff --git a/synapse/replication/tcp/client.py b/synapse/replication/tcp/client.py
index a44ceb00e71e..563ce0fc5311 100644
--- a/synapse/replication/tcp/client.py
+++ b/synapse/replication/tcp/client.py
@@ -168,7 +168,7 @@ def send_command(self, cmd):
         if self.connection:
             self.connection.send_command(cmd)
         else:
-            logger.warn("Queuing command as not connected: %r", cmd.NAME)
+            logger.warning("Queuing command as not connected: %r", cmd.NAME)
             self.pending_commands.append(cmd)
 
     def send_federation_ack(self, token):
diff --git a/synapse/replication/tcp/protocol.py b/synapse/replication/tcp/protocol.py
index 5ffdf2675df4..b64f3f44b560 100644
--- a/synapse/replication/tcp/protocol.py
+++ b/synapse/replication/tcp/protocol.py
@@ -249,7 +249,7 @@ def handle_command(self, cmd):
         return handler(cmd)
 
     def close(self):
-        logger.warn("[%s] Closing connection", self.id())
+        logger.warning("[%s] Closing connection", self.id())
         self.time_we_closed = self.clock.time_msec()
         self.transport.loseConnection()
         self.on_connection_closed()
diff --git a/synapse/rest/admin/__init__.py b/synapse/rest/admin/__init__.py
index 939418ee2b8c..5c2a2eb593a7 100644
--- a/synapse/rest/admin/__init__.py
+++ b/synapse/rest/admin/__init__.py
@@ -286,7 +286,7 @@ async def on_POST(self, request, room_id, event_id):
                 room_id, stream_ordering
             )
             if not r:
-                logger.warn(
+                logger.warning(
                     "[purge] purging events not possible: No event found "
                     "(received_ts %i => stream_ordering %i)",
                     ts,
diff --git a/synapse/rest/client/v1/login.py b/synapse/rest/client/v1/login.py
index 8414af08cb53..39a5c5e9de55 100644
--- a/synapse/rest/client/v1/login.py
+++ b/synapse/rest/client/v1/login.py
@@ -221,7 +221,7 @@ def _do_other_login(self, login_submission):
                 medium, address
             )
             if not user_id:
-                logger.warn(
+                logger.warning(
                     "unknown 3pid identifier medium %s, address %r", medium, address
                 )
                 raise LoginError(403, "", errcode=Codes.FORBIDDEN)
diff --git a/synapse/rest/client/v2_alpha/account.py b/synapse/rest/client/v2_alpha/account.py
index 80cf7126a05f..332d7138b1f5 100644
--- a/synapse/rest/client/v2_alpha/account.py
+++ b/synapse/rest/client/v2_alpha/account.py
@@ -71,7 +71,7 @@ def __init__(self, hs):
     def on_POST(self, request):
         if self.config.threepid_behaviour_email == ThreepidBehaviour.OFF:
             if self.config.local_threepid_handling_disabled_due_to_email_config:
-                logger.warn(
+                logger.warning(
                     "User password resets have been disabled due to lack of email config"
                 )
             raise SynapseError(
@@ -162,7 +162,7 @@ def on_GET(self, request, medium):
             )
         if self.config.threepid_behaviour_email == ThreepidBehaviour.OFF:
             if self.config.local_threepid_handling_disabled_due_to_email_config:
-                logger.warn(
+                logger.warning(
                     "Password reset emails have been disabled due to lack of an email config"
                 )
             raise SynapseError(
@@ -183,7 +183,7 @@ def on_GET(self, request, medium):
             # Perform a 302 redirect if next_link is set
             if next_link:
                 if next_link.startswith("file:///"):
-                    logger.warn(
+                    logger.warning(
                         "Not redirecting to next_link as it is a local file: address"
                     )
                 else:
@@ -350,7 +350,7 @@ def __init__(self, hs):
     def on_POST(self, request):
         if self.config.threepid_behaviour_email == ThreepidBehaviour.OFF:
             if self.config.local_threepid_handling_disabled_due_to_email_config:
-                logger.warn(
+                logger.warning(
                     "Adding emails have been disabled due to lack of an email config"
                 )
             raise SynapseError(
@@ -441,7 +441,7 @@ def on_POST(self, request):
             raise SynapseError(400, "MSISDN is already in use", Codes.THREEPID_IN_USE)
 
         if not self.hs.config.account_threepid_delegate_msisdn:
-            logger.warn(
+            logger.warning(
                 "No upstream msisdn account_threepid_delegate configured on the server to "
                 "handle this request"
             )
@@ -488,7 +488,7 @@ def __init__(self, hs):
     def on_GET(self, request):
         if self.config.threepid_behaviour_email == ThreepidBehaviour.OFF:
             if self.config.local_threepid_handling_disabled_due_to_email_config:
-                logger.warn(
+                logger.warning(
                     "Adding emails have been disabled due to lack of an email config"
                 )
             raise SynapseError(
@@ -515,7 +515,7 @@ def on_GET(self, request):
             # Perform a 302 redirect if next_link is set
             if next_link:
                 if next_link.startswith("file:///"):
-                    logger.warn(
+                    logger.warning(
                         "Not redirecting to next_link as it is a local file: address"
                     )
                 else:
diff --git a/synapse/rest/client/v2_alpha/register.py b/synapse/rest/client/v2_alpha/register.py
index 4f24a124a6b0..6c7d25d41171 100644
--- a/synapse/rest/client/v2_alpha/register.py
+++ b/synapse/rest/client/v2_alpha/register.py
@@ -106,7 +106,7 @@ def __init__(self, hs):
     def on_POST(self, request):
         if self.hs.config.threepid_behaviour_email == ThreepidBehaviour.OFF:
             if self.hs.config.local_threepid_handling_disabled_due_to_email_config:
-                logger.warn(
+                logger.warning(
                     "Email registration has been disabled due to lack of email config"
                 )
             raise SynapseError(
@@ -207,7 +207,7 @@ def on_POST(self, request):
             )
 
         if not self.hs.config.account_threepid_delegate_msisdn:
-            logger.warn(
+            logger.warning(
                 "No upstream msisdn account_threepid_delegate configured on the server to "
                 "handle this request"
             )
@@ -266,7 +266,7 @@ def on_GET(self, request, medium):
             )
         if self.config.threepid_behaviour_email == ThreepidBehaviour.OFF:
             if self.config.local_threepid_handling_disabled_due_to_email_config:
-                logger.warn(
+                logger.warning(
                     "User registration via email has been disabled due to lack of email config"
                 )
             raise SynapseError(
@@ -287,7 +287,7 @@ def on_GET(self, request, medium):
             # Perform a 302 redirect if next_link is set
             if next_link:
                 if next_link.startswith("file:///"):
-                    logger.warn(
+                    logger.warning(
                         "Not redirecting to next_link as it is a local file: address"
                     )
                 else:
@@ -480,7 +480,7 @@ def on_POST(self, request):
             # a password to work around a client bug where it sent
             # the 'initial_device_display_name' param alone, wiping out
             # the original registration params
-            logger.warn("Ignoring initial_device_display_name without password")
+            logger.warning("Ignoring initial_device_display_name without password")
             del body["initial_device_display_name"]
 
         session_id = self.auth_handler.get_session_id(body)
diff --git a/synapse/rest/client/v2_alpha/sync.py b/synapse/rest/client/v2_alpha/sync.py
index 541a6b0e1042..ccd8b17b23a5 100644
--- a/synapse/rest/client/v2_alpha/sync.py
+++ b/synapse/rest/client/v2_alpha/sync.py
@@ -394,7 +394,7 @@ def serialize(events):
             # We've had bug reports that events were coming down under the
             # wrong room.
             if event.room_id != room.room_id:
-                logger.warn(
+                logger.warning(
                     "Event %r is under room %r instead of %r",
                     event.event_id,
                     room.room_id,
diff --git a/synapse/rest/media/v1/media_repository.py b/synapse/rest/media/v1/media_repository.py
index b972e152a9dc..bd9186fe5026 100644
--- a/synapse/rest/media/v1/media_repository.py
+++ b/synapse/rest/media/v1/media_repository.py
@@ -363,7 +363,7 @@ def _download_remote_file(self, server_name, media_id, file_id):
                     },
                 )
             except RequestSendFailed as e:
-                logger.warn(
+                logger.warning(
                     "Request failed fetching remote media %s/%s: %r",
                     server_name,
                     media_id,
@@ -372,7 +372,7 @@ def _download_remote_file(self, server_name, media_id, file_id):
                 raise SynapseError(502, "Failed to fetch remote media")
 
             except HttpResponseException as e:
-                logger.warn(
+                logger.warning(
                     "HTTP error fetching remote media %s/%s: %s",
                     server_name,
                     media_id,
@@ -383,10 +383,12 @@ def _download_remote_file(self, server_name, media_id, file_id):
                 raise SynapseError(502, "Failed to fetch remote media")
 
             except SynapseError:
-                logger.warn("Failed to fetch remote media %s/%s", server_name, media_id)
+                logger.warning(
+                    "Failed to fetch remote media %s/%s", server_name, media_id
+                )
                 raise
             except NotRetryingDestination:
-                logger.warn("Not retrying destination %r", server_name)
+                logger.warning("Not retrying destination %r", server_name)
                 raise SynapseError(502, "Failed to fetch remote media")
             except Exception:
                 logger.exception(
@@ -691,7 +693,7 @@ def delete_old_remote_media(self, before_ts):
                 try:
                     os.remove(full_path)
                 except OSError as e:
-                    logger.warn("Failed to remove file: %r", full_path)
+                    logger.warning("Failed to remove file: %r", full_path)
                     if e.errno == errno.ENOENT:
                         pass
                     else:
diff --git a/synapse/rest/media/v1/preview_url_resource.py b/synapse/rest/media/v1/preview_url_resource.py
index 094ebad7707c..5a25b6b3fcda 100644
--- a/synapse/rest/media/v1/preview_url_resource.py
+++ b/synapse/rest/media/v1/preview_url_resource.py
@@ -136,7 +136,7 @@ async def _async_render_GET(self, request):
                         match = False
                         continue
             if match:
-                logger.warn("URL %s blocked by url_blacklist entry %s", url, entry)
+                logger.warning("URL %s blocked by url_blacklist entry %s", url, entry)
                 raise SynapseError(
                     403, "URL blocked by url pattern blacklist entry", Codes.UNKNOWN
                 )
@@ -208,7 +208,7 @@ def _do_preview(self, url, user, ts):
                 og["og:image:width"] = dims["width"]
                 og["og:image:height"] = dims["height"]
             else:
-                logger.warn("Couldn't get dims for %s" % url)
+                logger.warning("Couldn't get dims for %s" % url)
 
             # define our OG response for this media
         elif _is_html(media_info["media_type"]):
@@ -256,7 +256,7 @@ def _do_preview(self, url, user, ts):
                         og["og:image:width"] = dims["width"]
                         og["og:image:height"] = dims["height"]
                     else:
-                        logger.warn("Couldn't get dims for %s", og["og:image"])
+                        logger.warning("Couldn't get dims for %s", og["og:image"])
 
                     og["og:image"] = "mxc://%s/%s" % (
                         self.server_name,
@@ -267,7 +267,7 @@ def _do_preview(self, url, user, ts):
                 else:
                     del og["og:image"]
         else:
-            logger.warn("Failed to find any OG data in %s", url)
+            logger.warning("Failed to find any OG data in %s", url)
             og = {}
 
         logger.debug("Calculated OG for %s as %s", url, og)
@@ -319,7 +319,7 @@ def _download_url(self, url, user):
                 )
             except Exception as e:
                 # FIXME: pass through 404s and other error messages nicely
-                logger.warn("Error downloading %s: %r", url, e)
+                logger.warning("Error downloading %s: %r", url, e)
 
                 raise SynapseError(
                     500,
@@ -400,7 +400,7 @@ def _expire_url_cache_data(self):
             except OSError as e:
                 # If the path doesn't exist, meh
                 if e.errno != errno.ENOENT:
-                    logger.warn("Failed to remove media: %r: %s", media_id, e)
+                    logger.warning("Failed to remove media: %r: %s", media_id, e)
                     continue
 
             removed_media.append(media_id)
@@ -432,7 +432,7 @@ def _expire_url_cache_data(self):
             except OSError as e:
                 # If the path doesn't exist, meh
                 if e.errno != errno.ENOENT:
-                    logger.warn("Failed to remove media: %r: %s", media_id, e)
+                    logger.warning("Failed to remove media: %r: %s", media_id, e)
                     continue
 
             try:
@@ -448,7 +448,7 @@ def _expire_url_cache_data(self):
             except OSError as e:
                 # If the path doesn't exist, meh
                 if e.errno != errno.ENOENT:
-                    logger.warn("Failed to remove media: %r: %s", media_id, e)
+                    logger.warning("Failed to remove media: %r: %s", media_id, e)
                     continue
 
             removed_media.append(media_id)
diff --git a/synapse/rest/media/v1/thumbnail_resource.py b/synapse/rest/media/v1/thumbnail_resource.py
index 08329884ac73..931ce79be830 100644
--- a/synapse/rest/media/v1/thumbnail_resource.py
+++ b/synapse/rest/media/v1/thumbnail_resource.py
@@ -182,7 +182,7 @@ def _select_or_generate_local_thumbnail(
         if file_path:
             yield respond_with_file(request, desired_type, file_path)
         else:
-            logger.warn("Failed to generate thumbnail")
+            logger.warning("Failed to generate thumbnail")
             respond_404(request)
 
     @defer.inlineCallbacks
@@ -245,7 +245,7 @@ def _select_or_generate_remote_thumbnail(
         if file_path:
             yield respond_with_file(request, desired_type, file_path)
         else:
-            logger.warn("Failed to generate thumbnail")
+            logger.warning("Failed to generate thumbnail")
             respond_404(request)
 
     @defer.inlineCallbacks
diff --git a/synapse/server_notices/resource_limits_server_notices.py b/synapse/server_notices/resource_limits_server_notices.py
index c0e7f475c929..9fae2e0afe62 100644
--- a/synapse/server_notices/resource_limits_server_notices.py
+++ b/synapse/server_notices/resource_limits_server_notices.py
@@ -83,7 +83,7 @@ def maybe_send_server_notice_to_user(self, user_id):
         room_id = yield self._server_notices_manager.get_notice_room_for_user(user_id)
 
         if not room_id:
-            logger.warn("Failed to get server notices room")
+            logger.warning("Failed to get server notices room")
             return
 
         yield self._check_and_set_tags(user_id, room_id)
diff --git a/synapse/storage/_base.py b/synapse/storage/_base.py
index f5906fcd5468..1a2b7ebe25cf 100644
--- a/synapse/storage/_base.py
+++ b/synapse/storage/_base.py
@@ -494,7 +494,7 @@ def runInteraction(self, desc, func, *args, **kwargs):
         exception_callbacks = []
 
         if LoggingContext.current_context() == LoggingContext.sentinel:
-            logger.warn("Starting db txn '%s' from sentinel context", desc)
+            logger.warning("Starting db txn '%s' from sentinel context", desc)
 
         try:
             result = yield self.runWithConnection(
@@ -532,7 +532,7 @@ def runWithConnection(self, func, *args, **kwargs):
         """
         parent_context = LoggingContext.current_context()
         if parent_context == LoggingContext.sentinel:
-            logger.warn(
+            logger.warning(
                 "Starting db connection from sentinel context: metrics will be lost"
             )
             parent_context = None
@@ -719,7 +719,7 @@ def _simple_upsert(
                     raise
 
                 # presumably we raced with another transaction: let's retry.
-                logger.warn(
+                logger.warning(
                     "IntegrityError when upserting into %s; retrying: %s", table, e
                 )
 
diff --git a/synapse/storage/data_stores/main/pusher.py b/synapse/storage/data_stores/main/pusher.py
index f005c1ae0a5c..d76861cdc0b5 100644
--- a/synapse/storage/data_stores/main/pusher.py
+++ b/synapse/storage/data_stores/main/pusher.py
@@ -44,7 +44,7 @@ def _decode_pushers_rows(self, rows):
 
                 r["data"] = json.loads(dataJson)
             except Exception as e:
-                logger.warn(
+                logger.warning(
                     "Invalid JSON in data for pusher %d: %s, %s",
                     r["id"],
                     dataJson,
diff --git a/synapse/storage/data_stores/main/search.py b/synapse/storage/data_stores/main/search.py
index 0e08497452f8..a59b8331e170 100644
--- a/synapse/storage/data_stores/main/search.py
+++ b/synapse/storage/data_stores/main/search.py
@@ -196,7 +196,7 @@ def create_index(conn):
                         " ON event_search USING GIN (vector)"
                     )
                 except psycopg2.ProgrammingError as e:
-                    logger.warn(
+                    logger.warning(
                         "Ignoring error %r when trying to switch from GIST to GIN", e
                     )
 
diff --git a/synapse/util/async_helpers.py b/synapse/util/async_helpers.py
index b60a604474bd..5c4de2e69f23 100644
--- a/synapse/util/async_helpers.py
+++ b/synapse/util/async_helpers.py
@@ -309,7 +309,7 @@ def eb(e):
                 )
 
             else:
-                logger.warn(
+                logger.warning(
                     "Unexpected exception waiting for linearizer lock %r for key %r",
                     self.name,
                     key,
diff --git a/synapse/util/caches/__init__.py b/synapse/util/caches/__init__.py
index 43fd65d69380..da5077b47105 100644
--- a/synapse/util/caches/__init__.py
+++ b/synapse/util/caches/__init__.py
@@ -107,7 +107,7 @@ def collect(self):
                 if collect_callback:
                     collect_callback()
             except Exception as e:
-                logger.warn("Error calculating metrics for %s: %s", cache_name, e)
+                logger.warning("Error calculating metrics for %s: %s", cache_name, e)
                 raise
 
             yield GaugeMetricFamily("__unused", "")
diff --git a/synapse/util/metrics.py b/synapse/util/metrics.py
index 4b1bcdf23c78..3286804322e1 100644
--- a/synapse/util/metrics.py
+++ b/synapse/util/metrics.py
@@ -119,7 +119,7 @@ def __exit__(self, exc_type, exc_val, exc_tb):
         context = LoggingContext.current_context()
 
         if context != self.start_context:
-            logger.warn(
+            logger.warning(
                 "Context has unexpectedly changed from '%s' to '%s'. (%r)",
                 self.start_context,
                 context,
@@ -128,7 +128,7 @@ def __exit__(self, exc_type, exc_val, exc_tb):
             return
 
         if not context:
-            logger.warn("Expected context. (%r)", self.name)
+            logger.warning("Expected context. (%r)", self.name)
             return
 
         current = context.get_resource_usage()
@@ -140,7 +140,7 @@ def __exit__(self, exc_type, exc_val, exc_tb):
             block_db_txn_duration.labels(self.name).inc(usage.db_txn_duration_sec)
             block_db_sched_duration.labels(self.name).inc(usage.db_sched_duration_sec)
         except ValueError:
-            logger.warn(
+            logger.warning(
                 "Failed to save metrics! OLD: %r, NEW: %r", self.start_usage, current
             )
 
diff --git a/synapse/util/rlimit.py b/synapse/util/rlimit.py
index 6c0f2bb0cf3c..207cd17c2a50 100644
--- a/synapse/util/rlimit.py
+++ b/synapse/util/rlimit.py
@@ -33,4 +33,4 @@ def change_resource_limit(soft_file_no):
             resource.RLIMIT_CORE, (resource.RLIM_INFINITY, resource.RLIM_INFINITY)
         )
     except (ValueError, resource.error) as e:
-        logger.warn("Failed to set file or core limit: %s", e)
+        logger.warning("Failed to set file or core limit: %s", e)