diff --git a/openstackclient/compute/v2/server.py b/openstackclient/compute/v2/server.py
index 1eee828d9b..b4488c3f16 100644
--- a/openstackclient/compute/v2/server.py
+++ b/openstackclient/compute/v2/server.py
@@ -4267,7 +4267,7 @@ release the new server and restart the old one."""
             metavar='<server>',
             help=_('Server (name or ID)'),
         )
-        phase_group = parser.add_mutually_exclusive_group()
+        phase_group = parser.add_mutually_exclusive_group(required=True)
         phase_group.add_argument(
             '--flavor',
             metavar='<flavor>',
diff --git a/openstackclient/tests/unit/compute/v2/test_server.py b/openstackclient/tests/unit/compute/v2/test_server.py
index 0597312510..8da3516769 100644
--- a/openstackclient/tests/unit/compute/v2/test_server.py
+++ b/openstackclient/tests/unit/compute/v2/test_server.py
@@ -7896,15 +7896,13 @@ class TestServerResize(compute_fakes.TestComputev2):
             ('server', self.server.id),
         ]
 
-        parsed_args = self.check_parser(self.cmd, arglist, verifylist)
-        result = self.cmd.take_action(parsed_args)
-
-        self.compute_client.find_server.assert_called_once_with(
-            self.server.id, ignore_missing=False
+        self.assertRaises(
+            test_utils.ParserException,
+            self.check_parser,
+            self.cmd,
+            arglist,
+            verifylist,
         )
-        self.compute_client.find_flavor.assert_not_called()
-        self.compute_client.resize_server.assert_not_called()
-        self.assertIsNone(result)
 
     def test_server_resize(self):
         arglist = [
diff --git a/releasenotes/notes/fix-resize-server-args-required-2e9013bcbf207f6a.yaml b/releasenotes/notes/fix-resize-server-args-required-2e9013bcbf207f6a.yaml
new file mode 100644
index 0000000000..e1faf7e601
--- /dev/null
+++ b/releasenotes/notes/fix-resize-server-args-required-2e9013bcbf207f6a.yaml
@@ -0,0 +1,8 @@
+---
+fixes:
+  - |
+    The ``openstack server resize`` command now requires the ``--flavor``
+    option or one of the deprecated ``--confirm`` or ``--revert`` options
+    to be provided.
+    Previously, the command would silently exit successfully without
+    performing any action if no option was provided.