diff --git a/doc/source/serve/api/index.md b/doc/source/serve/api/index.md
index af6540bd5af5..b4dd44adb1e2 100644
--- a/doc/source/serve/api/index.md
+++ b/doc/source/serve/api/index.md
@@ -141,6 +141,7 @@ See the [model composition guide](serve-model-composition) for how to update cod
    serve.grpc_util.RayServegRPCContext
    serve.exceptions.BackPressureError
    serve.exceptions.RayServeException
+   serve.exceptions.RayServeConfigException
    serve.exceptions.RequestCancelledError
    serve.exceptions.DeploymentUnavailableError
 ```
diff --git a/doc/source/serve/production-guide/config.md b/doc/source/serve/production-guide/config.md
index fa5eff346fe5..fe385f2c3697 100644
--- a/doc/source/serve/production-guide/config.md
+++ b/doc/source/serve/production-guide/config.md
@@ -60,6 +60,8 @@ The `proxy_location` field configures where to run proxies to handle traffic to
 - HeadOnly: Only run a single proxy on the head node.
 - Disabled: Don't run proxies at all. Set this value if you are only making calls to your applications using deployment handles.
 
+Note that the Proxy config is global to your Ray cluster, and you can't update it during runtime.
+
 (http-config)=
 
 ## HTTP config 
diff --git a/python/ray/dashboard/modules/serve/serve_head.py b/python/ray/dashboard/modules/serve/serve_head.py
index 205648d74dc3..21851f4de4b7 100644
--- a/python/ray/dashboard/modules/serve/serve_head.py
+++ b/python/ray/dashboard/modules/serve/serve_head.py
@@ -170,11 +170,6 @@ async def put_all_applications(self, req: Request) -> Response:
                 global_logging_config=config.logging_config,
             )
 
-        # Serve ignores HTTP options if it was already running when
-        # serve_start_async() is called. Therefore we validate that no
-        # existing HTTP options are updated and print warning in case they are
-        self.validate_http_options(client, full_http_options)
-
         try:
             if config.logging_config:
                 client.update_global_logging_config(config.logging_config)
@@ -269,22 +264,6 @@ async def scale_deployment(self, req: Request) -> Response:
                     {"error": "Internal Server Error"}, 503
                 )
 
-    def validate_http_options(self, client, http_options):
-        divergent_http_options = []
-
-        for option, new_value in http_options.items():
-            prev_value = getattr(client.http_config, option)
-            if prev_value != new_value:
-                divergent_http_options.append(option)
-
-        if divergent_http_options:
-            logger.warning(
-                "Serve is already running on this Ray cluster and "
-                "it's not possible to update its HTTP options without "
-                "restarting it. Following options are attempted to be "
-                f"updated: {divergent_http_options}."
-            )
-
     async def get_serve_controller(self):
         """Gets the ServeController to the this cluster's Serve app.
 
diff --git a/python/ray/dashboard/modules/serve/tests/test_serve_dashboard.py b/python/ray/dashboard/modules/serve/tests/test_serve_dashboard.py
index 47be34577b47..05a9cb13eb91 100644
--- a/python/ray/dashboard/modules/serve/tests/test_serve_dashboard.py
+++ b/python/ray/dashboard/modules/serve/tests/test_serve_dashboard.py
@@ -887,8 +887,6 @@ def test_scale_deployment_retention_during_serve_controller_restart(
         self, ray_start_stop
     ):
         """Test that replica counts set via /scale are retained after serve controller restart."""
-        serve.start()
-
         with tempfile.TemporaryDirectory() as tmpdir:
             tmp_path = Path(tmpdir)
 
diff --git a/python/ray/dashboard/modules/serve/tests/test_serve_dashboard_2.py b/python/ray/dashboard/modules/serve/tests/test_serve_dashboard_2.py
index a21cad86ad32..52ce2a16563c 100644
--- a/python/ray/dashboard/modules/serve/tests/test_serve_dashboard_2.py
+++ b/python/ray/dashboard/modules/serve/tests/test_serve_dashboard_2.py
@@ -76,11 +76,10 @@ def test_serve_namespace(ray_start_stop):
 def test_put_with_http_options(ray_start_stop, option, override):
     """Submits a config with HTTP options specified.
 
-    Trying to submit a config to the serve agent with the HTTP options modified should
-    NOT fail:
+    Trying to submit a config to the serve agent with the HTTP options modified should fail:
       - If Serve is NOT running, HTTP options will be honored when starting Serve
-      - If Serve is running, HTTP options will be ignored, and warning will be logged
-      urging users to restart Serve if they want their options to take effect
+      - If Serve is running and HTTP options are attempted to be changed, deployment will fail,
+        forcing users to restart Serve if they want their options to take effect.
     """
 
     pizza_import_path = "ray.serve.tests.test_config_files.pizza.serve_dag"
@@ -126,7 +125,7 @@ def test_put_with_http_options(ray_start_stop, option, override):
     put_response = requests.put(
         SERVE_HEAD_URL, json=updated_serve_config_json, timeout=5
     )
-    assert put_response.status_code == 200
+    assert put_response.status_code == 500
 
     # Fetch Serve status and confirm that HTTP options are unchanged
     get_response = requests.get(SERVE_HEAD_URL, timeout=5)
diff --git a/python/ray/serve/_private/api.py b/python/ray/serve/_private/api.py
index 60b097d4c001..0e2b66bd930d 100644
--- a/python/ray/serve/_private/api.py
+++ b/python/ray/serve/_private/api.py
@@ -14,37 +14,54 @@
     SERVE_NAMESPACE,
 )
 from ray.serve._private.default_impl import get_controller_impl
-from ray.serve.config import HTTPOptions, gRPCOptions
+from ray.serve.config import DeploymentMode, HTTPOptions, ProxyLocation, gRPCOptions
 from ray.serve.context import _get_global_client, _set_global_client
 from ray.serve.deployment import Application
-from ray.serve.exceptions import RayServeException
+from ray.serve.exceptions import RayServeConfigException, RayServeException
 from ray.serve.schema import LoggingConfig
 
 logger = logging.getLogger(SERVE_LOGGER_NAME)
 
 
 def _check_http_options(
-    client: ServeControllerClient, http_options: Union[dict, HTTPOptions]
+    curr_http_options: HTTPOptions, new_http_options: Union[dict, HTTPOptions]
 ) -> None:
-    if http_options:
-        client_http_options = client.http_config
-        new_http_options = (
-            http_options
-            if isinstance(http_options, HTTPOptions)
-            else HTTPOptions.parse_obj(http_options)
-        )
-        different_fields = []
-        all_http_option_fields = new_http_options.__dict__
-        for field in all_http_option_fields:
-            if getattr(new_http_options, field) != getattr(client_http_options, field):
-                different_fields.append(field)
-
-        if len(different_fields):
-            logger.warning(
-                "The new client HTTP config differs from the existing one "
-                f"in the following fields: {different_fields}. "
-                "The new HTTP config is ignored."
+    def maybe_restore_proxy_location(prev_value, new_value) -> (str, str):
+        if isinstance(prev_value, DeploymentMode) and isinstance(
+            new_value, DeploymentMode
+        ):
+            # restore ProxyLocation as this is the property user configured
+            prev_value = ProxyLocation._from_deployment_mode(prev_value).value
+            new_value = ProxyLocation._from_deployment_mode(new_value).value
+        return prev_value, new_value
+
+    if not new_http_options:
+        return
+
+    if isinstance(new_http_options, HTTPOptions):
+        new_http_options = new_http_options.dict(exclude_unset=True)
+
+    diff_http_options = {}
+    for option, new_value in new_http_options.items():
+        if not hasattr(curr_http_options, option):
+            valid_fields = (
+                getattr(HTTPOptions, "__fields__", None)
+                or getattr(HTTPOptions, "model_fields", {}).keys()
+            )
+            raise RayServeConfigException(
+                f"Invalid http_options key '{option}'. Valid keys: {sorted(valid_fields)}"
             )
+        prev_value = getattr(curr_http_options, option)
+        if prev_value != new_value:
+            prev_value, new_value = maybe_restore_proxy_location(prev_value, new_value)
+            diff_http_options[option] = {"previous": prev_value, "new": new_value}
+    if diff_http_options:
+        raise RayServeConfigException(
+            "Attempt to update `http_options` or `proxy_location` has been detected! "
+            f"Attempted updates: `{diff_http_options}`. "
+            "HTTP config is global to your Ray cluster, and you can't update it during runtime. "
+            "Please restart Ray Serve to apply the change."
+        )
 
 
 def _start_controller(
@@ -136,7 +153,7 @@ async def serve_start_async(
             " New http options will not be applied."
         )
         if http_options:
-            _check_http_options(client, http_options)
+            _check_http_options(client.http_config, http_options)
         return client
     except RayServeException:
         pass
@@ -210,7 +227,7 @@ def serve_start(
             " New http options will not be applied."
         )
         if http_options:
-            _check_http_options(client, http_options)
+            _check_http_options(client.http_config, http_options)
         return client
     except RayServeException:
         pass
diff --git a/python/ray/serve/api.py b/python/ray/serve/api.py
index d18bbd3d0e69..ba783e818fdd 100644
--- a/python/ray/serve/api.py
+++ b/python/ray/serve/api.py
@@ -588,7 +588,6 @@ def _run_many(
         return [b.deployment_handles[b.ingress_deployment_name] for b in built_apps]
     else:
         client = _private_api.serve_start(
-            http_options={"location": "EveryNode"},
             global_logging_config=None,
         )
 
diff --git a/python/ray/serve/config.py b/python/ray/serve/config.py
index 6aa7ac54317b..540424642981 100644
--- a/python/ray/serve/config.py
+++ b/python/ray/serve/config.py
@@ -573,8 +573,8 @@ class HTTPOptions(BaseModel):
 
         - "HeadOnly": start one HTTP server on the head node. Serve
           assumes the head node is the node you executed serve.start
-          on. This is the default.
-        - "EveryNode": start one HTTP server per node.
+          on.
+        - "EveryNode": start one HTTP server per node. This is the default.
         - "NoServer": disable HTTP server.
 
     - num_cpus: [DEPRECATED] The number of CPU cores to reserve for each
@@ -584,7 +584,7 @@ class HTTPOptions(BaseModel):
     host: Optional[str] = DEFAULT_HTTP_HOST
     port: int = DEFAULT_HTTP_PORT
     middlewares: List[Any] = []
-    location: Optional[DeploymentMode] = DeploymentMode.HeadOnly
+    location: Optional[DeploymentMode] = DeploymentMode.EveryNode
     num_cpus: int = 0
     root_url: str = ""
     root_path: str = ""
diff --git a/python/ray/serve/exceptions.py b/python/ray/serve/exceptions.py
index 10033b28f9cd..9db5ffb6d942 100644
--- a/python/ray/serve/exceptions.py
+++ b/python/ray/serve/exceptions.py
@@ -10,6 +10,13 @@ class RayServeException(Exception):
     pass
 
 
+@PublicAPI(stability="alpha")
+class RayServeConfigException(Exception):
+    """Raised when a Serve config failed to be applied."""
+
+    pass
+
+
 @PublicAPI(stability="alpha")
 class BackPressureError(RayServeException):
     """Raised when max_queued_requests is exceeded on a DeploymentHandle."""
diff --git a/python/ray/serve/tests/conftest.py b/python/ray/serve/tests/conftest.py
index 6bf5243eabb8..69e7392e4b91 100644
--- a/python/ray/serve/tests/conftest.py
+++ b/python/ray/serve/tests/conftest.py
@@ -21,7 +21,7 @@
     check_ray_stopped,
     start_telemetry_app,
 )
-from ray.serve.config import HTTPOptions, ProxyLocation, gRPCOptions
+from ray.serve.config import HTTPOptions, gRPCOptions
 from ray.serve.context import _get_global_client
 from ray.tests.conftest import (  # noqa
     external_redis,
@@ -148,7 +148,6 @@ def _shared_serve_instance():
         _system_config={"metrics_report_interval_ms": 1000, "task_retry_delay_ms": 50},
     )
     serve.start(
-        proxy_location=ProxyLocation.HeadOnly,
         http_options={"host": "0.0.0.0"},
         grpc_options={
             "port": 9000,
diff --git a/python/ray/serve/tests/test_api_2.py b/python/ray/serve/tests/test_api_2.py
index 65fd4c63e28e..9f90507b3dcd 100644
--- a/python/ray/serve/tests/test_api_2.py
+++ b/python/ray/serve/tests/test_api_2.py
@@ -3,8 +3,12 @@
 import ray
 from ray import serve
 from ray._common.network_utils import build_address
+from ray.serve import HTTPOptions
+from ray.serve._private.api import _check_http_options
 from ray.serve._private.common import RequestProtocol
 from ray.serve._private.test_utils import get_application_urls
+from ray.serve.config import DeploymentMode
+from ray.serve.exceptions import RayServeConfigException
 
 
 def test_get_application_urls(serve_instance):
@@ -61,6 +65,59 @@ def f():
     ]
 
 
+def test_serve_start(serve_instance):
+    serve.start()  # success with default params
+    with pytest.raises(
+        RayServeConfigException,
+        match=r"{'host': {'previous': '0.0.0.0', 'new': '127.0.0.1'}}",
+    ):
+        serve.start(http_options={"host": "127.0.0.1"})
+
+
+def test_check_http_options():
+    curr = HTTPOptions()
+    _check_http_options(curr, None)
+    _check_http_options(curr, {})
+
+    curr = HTTPOptions()
+    new = HTTPOptions()
+    _check_http_options(curr, new)
+    _check_http_options({}, {})
+    _check_http_options(None, None)
+
+    curr = HTTPOptions()
+    new = {"foo": 123}
+    with pytest.raises(RayServeConfigException) as exc:
+        _check_http_options(curr, new)
+    msg = str(exc.value)
+    assert "Invalid http_options key 'foo'." in msg
+
+    curr = HTTPOptions(host="127.0.0.1", port=8000)
+    new = {"host": "0.0.0.0"}
+    with pytest.raises(RayServeConfigException) as exc:
+        _check_http_options(curr, new)
+    msg = str(exc.value)
+    assert "Attempted updates:" in msg
+    assert "`{'host': {'previous': '127.0.0.1', 'new': '0.0.0.0'}}`" in msg
+
+    curr = HTTPOptions(host="127.0.0.1", port=8000, root_path="")
+    new = {"host": "0.0.0.0", "port": 8001}
+    with pytest.raises(RayServeConfigException) as exc:
+        _check_http_options(curr, new)
+    msg = str(exc.value)
+    assert (
+        "`{'host': {'previous': '127.0.0.1', 'new': '0.0.0.0'}, "
+        "'port': {'previous': 8000, 'new': 8001}}`"
+    ) in msg
+
+    curr = HTTPOptions(location=DeploymentMode.HeadOnly)
+    new = HTTPOptions(location=DeploymentMode.EveryNode)
+    with pytest.raises(RayServeConfigException) as exc:
+        _check_http_options(curr, new)
+    msg = str(exc.value)
+    assert "`{'location': {'previous': 'HeadOnly', 'new': 'EveryNode'}}`" in msg
+
+
 if __name__ == "__main__":
     import sys
 
diff --git a/python/ray/serve/tests/test_cli.py b/python/ray/serve/tests/test_cli.py
index 0c57e0197942..6a0f1272540d 100644
--- a/python/ray/serve/tests/test_cli.py
+++ b/python/ray/serve/tests/test_cli.py
@@ -275,6 +275,40 @@ def test_deploy_bad_v2_config(serve_instance):
     assert "Please ensure each application's route_prefix is unique" in output
 
 
+@pytest.mark.skipif(sys.platform == "win32", reason="File path incorrect on Windows.")
+def test_deploy_with_different_http_options(serve_instance, tmp_path):
+    config_path = tmp_path / "config.yaml"
+    config = {
+        "proxy_location": "HeadOnly",
+        "http_options": {
+            "host": "0.0.0.1",
+            "port": 8001,
+        },
+        "applications": [],
+    }
+    with open(config_path, "w") as f:
+        yaml.dump(config, f)
+
+    with pytest.raises(subprocess.CalledProcessError) as e:
+        subprocess.check_output(
+            ["serve", "deploy", str(config_path)], stderr=subprocess.STDOUT
+        )
+    error = e.value.output.decode("utf-8")
+    assert "RayServeConfigException" in error
+    assert (
+        "Attempt to update `http_options` or `proxy_location` has been detected!"
+        in error
+    )
+    assert "'host': {'previous': '0.0.0.0', 'new': '0.0.0.1'}" in error
+    assert "'port': {'previous': 8000, 'new': 8001}" in error
+    assert "'location': {'previous': 'EveryNode', 'new': 'HeadOnly'}" in error
+    assert (
+        "HTTP config is global to your Ray cluster, and you can't update it during runtime."
+        in error
+    )
+    assert "Please restart Ray Serve to apply the change." in error
+
+
 @pytest.mark.skipif(sys.platform == "win32", reason="File path incorrect on Windows.")
 def test_deploy_multi_app_builder_with_args(serve_instance):
     """Deploys a config file containing multiple applications that take arguments."""
diff --git a/python/ray/serve/tests/test_cli_2.py b/python/ray/serve/tests/test_cli_2.py
index df267c69d8d0..9c806cfac30c 100644
--- a/python/ray/serve/tests/test_cli_2.py
+++ b/python/ray/serve/tests/test_cli_2.py
@@ -58,7 +58,7 @@ def check_http_response(expected_text: str, json: Optional[Dict] = None):
 
 
 def test_start_shutdown(ray_start_stop):
-    subprocess.check_output(["serve", "start"])
+    subprocess.check_output(["serve", "start", "--http-host", "0.0.0.0"])
     # deploy a simple app
     import_path = "ray.serve.tests.test_config_files.arg_builders.build_echo_app"
 
@@ -253,7 +253,7 @@ def test_idempotence_after_controller_death(ray_start_stop, use_command: bool):
     deploy_response = subprocess.check_output(["serve", "deploy", config_file_name])
     assert success_message_fragment in deploy_response
 
-    serve.start()
+    serve.start(http_options={"host": "0.0.0.0"})
     wait_for_condition(
         lambda: len(list_actors(filters=[("state", "=", "ALIVE")])) == 4,
         timeout=15,
@@ -274,7 +274,7 @@ def test_idempotence_after_controller_death(ray_start_stop, use_command: bool):
     assert success_message_fragment in deploy_response
 
     # Restore testing controller
-    serve.start()
+    serve.start(http_options={"host": "0.0.0.0"})
     wait_for_condition(
         lambda: len(list_actors(filters=[("state", "=", "ALIVE")])) == 4,
         timeout=15,
diff --git a/python/ray/serve/tests/test_controller.py b/python/ray/serve/tests/test_controller.py
index 01f410999930..df091a960cc9 100644
--- a/python/ray/serve/tests/test_controller.py
+++ b/python/ray/serve/tests/test_controller.py
@@ -124,7 +124,7 @@ def autoscaling_app():
                 "worker_id": controller_details.worker_id,
                 "log_file_path": controller_details.log_file_path,
             },
-            "proxy_location": "HeadOnly",
+            "proxy_location": "EveryNode",
             "http_options": {"host": "0.0.0.0"},
             "grpc_options": {
                 "port": 9000,
diff --git a/python/ray/serve/tests/test_standalone.py b/python/ray/serve/tests/test_standalone.py
index dfa84420c30f..85eb6e4e9f06 100644
--- a/python/ray/serve/tests/test_standalone.py
+++ b/python/ray/serve/tests/test_standalone.py
@@ -31,6 +31,7 @@
 from ray.serve._private.utils import block_until_http_ready, format_actor_name
 from ray.serve.config import DeploymentMode, HTTPOptions, ProxyLocation
 from ray.serve.context import _get_global_client
+from ray.serve.exceptions import RayServeConfigException
 from ray.serve.schema import ServeApplicationSchema, ServeDeploySchema
 from ray.util.state import list_actors
 
@@ -702,11 +703,11 @@ class A:
         driver_template.format(address=address, namespace="test_namespace1", port=8000)
     )
     run_string_as_driver(
-        driver_template.format(address=address, namespace="test_namespace2", port=8001)
+        driver_template.format(address=address, namespace="test_namespace2", port=8000)
     )
 
 
-def test_serve_start_different_http_checkpoint_options_warning(
+def test_serve_start_different_http_checkpoint_options_error(
     ray_shutdown, propagate_logs, caplog
 ):
     logger = logging.getLogger("ray.serve")
@@ -726,13 +727,10 @@ def emit(self, record):
     # create a different config
     test_http = dict(host="127.1.1.8", port=_get_random_port())
 
-    serve.start(http_options=test_http)
-
-    for test_config, msg in zip([["host", "port"]], warning_msg):
-        for test_msg in test_config:
-            if "Autoscaling metrics pusher thread" in msg:
-                continue
-            assert test_msg in msg
+    with pytest.raises(
+        RayServeConfigException, match="Attempt to update `http_options`"
+    ):
+        serve.start(http_options=test_http)
 
 
 def test_recovering_controller_no_redeploy():
@@ -900,7 +898,7 @@ def test_build_app_task_uses_zero_cpus(ray_shutdown):
         {
             "proxy_location": None,
             "http_options": HTTPOptions(),
-            "expected": HTTPOptions(location=DeploymentMode.HeadOnly),
+            "expected": HTTPOptions(location=DeploymentMode.EveryNode),
         },  # using default location from HTTPOptions
         {
             "proxy_location": None,
diff --git a/python/ray/serve/tests/test_telemetry_1.py b/python/ray/serve/tests/test_telemetry_1.py
index 6524e9679c9d..93203533dc56 100644
--- a/python/ray/serve/tests/test_telemetry_1.py
+++ b/python/ray/serve/tests/test_telemetry_1.py
@@ -105,13 +105,14 @@ def test_rest_api(manage_ray_with_telemetry, tmp_dir):
     check_telemetry(ServeUsageTag.REST_API_VERSION, expected=None)
 
     config = {
+        "http_options": {"host": "127.0.0.1"},
         "applications": [
             {
                 "name": "stub_app",
                 "import_path": "ray.serve.tests.test_telemetry_1.stub_app",
                 "route_prefix": "/stub",
             },
-        ]
+        ],
     }
     config_file_path = f"{tmp_dir}/config.yaml"
     with open(config_file_path, "w+") as f:
@@ -149,7 +150,7 @@ def test_rest_api(manage_ray_with_telemetry, tmp_dir):
     assert ServeUsageTag.AUTO_NUM_REPLICAS_USED.get_value_from_report(report) is None
 
     # Check that app deletions are tracked.
-    new_config = {"applications": []}
+    new_config = {"http_options": {"host": "127.0.0.1"}, "applications": []}
 
     with open(config_file_path, "w+") as f:
         yaml.safe_dump(new_config, f)
diff --git a/python/ray/serve/tests/unit/test_config.py b/python/ray/serve/tests/unit/test_config.py
index 5f2d3902e2c6..ad4e8293e017 100644
--- a/python/ray/serve/tests/unit/test_config.py
+++ b/python/ray/serve/tests/unit/test_config.py
@@ -675,13 +675,13 @@ def test_prepare_imperative_http_options():
         proxy_location=None,
         http_options=HTTPOptions(**{}),
     ) == HTTPOptions(
-        location=DeploymentMode.HeadOnly
+        location=DeploymentMode.EveryNode
     )  # in this case we can't know whether location was provided or not
 
     assert prepare_imperative_http_options(
         proxy_location=None,
         http_options=HTTPOptions(),
-    ) == HTTPOptions(location=DeploymentMode.HeadOnly)
+    ) == HTTPOptions(location=DeploymentMode.EveryNode)
 
     assert prepare_imperative_http_options(
         proxy_location=None,