diff --git a/internal/temporalcli/commands.gen.go b/internal/temporalcli/commands.gen.go
index 0165f6e30..7dae4ab5b 100644
--- a/internal/temporalcli/commands.gen.go
+++ b/internal/temporalcli/commands.gen.go
@@ -2152,12 +2152,12 @@ func NewTemporalOperatorNamespaceUpdateCommand(cctx *CommandContext, parent *Tem
 	s.Command.Use = "update [flags]"
 	s.Command.Short = "Update a Namespace"
 	if hasHighlighting {
-		s.Command.Long = "Update a Namespace using properties you specify.\n\n\x1b[1mtemporal operator namespace update [options]\x1b[0m\n\nAssign a Namespace's active Cluster (Service):\n\n\x1b[1mtemporal operator namespace update \\\n    --namespace YourNamespaceName \\\n    --active-cluster NewActiveCluster\x1b[0m\n\nPromote a Namespace for multi-region data replication:\n\n\x1b[1mtemporal operator namespace update \\\n    --namespace YourNamespaceName \\\n    --promote-global\x1b[0m\n\nYou may update archives that were previously enabled or disabled. Note: URI\nvalues for archival states can't be changed once enabled.\n\n\x1b[1mtemporal operator namespace update \\\n    --namespace YourNamespaceName \\\n    --history-archival-state enabled \\\n    --visibility-archival-state disabled\x1b[0m"
+		s.Command.Long = "Update a Namespace using properties you specify.\n\n\x1b[1mtemporal operator namespace update [options]\x1b[0m\n\nAssign a Namespace's active Cluster (Service):\n\n\x1b[1mtemporal operator namespace update \\\n    --namespace YourNamespaceName \\\n    --active-cluster NewActiveCluster\x1b[0m\n\nActive Cluster changes cannot be combined with other Namespace updates.\nUpdate Namespace configuration, including the replication Cluster list,\nbefore changing the active Cluster in a separate command.\n\nPromote a Namespace for multi-region data replication:\n\n\x1b[1mtemporal operator namespace update \\\n    --namespace YourNamespaceName \\\n    --promote-global\x1b[0m\n\nYou may update archives that were previously enabled or disabled. Note: URI\nvalues for archival states can't be changed once enabled.\n\n\x1b[1mtemporal operator namespace update \\\n    --namespace YourNamespaceName \\\n    --history-archival-state enabled \\\n    --visibility-archival-state disabled\x1b[0m"
 	} else {
-		s.Command.Long = "Update a Namespace using properties you specify.\n\n```\ntemporal operator namespace update [options]\n```\n\nAssign a Namespace's active Cluster (Service):\n\n```\ntemporal operator namespace update \\\n    --namespace YourNamespaceName \\\n    --active-cluster NewActiveCluster\n```\n\nPromote a Namespace for multi-region data replication:\n\n```\ntemporal operator namespace update \\\n    --namespace YourNamespaceName \\\n    --promote-global\n```\n\nYou may update archives that were previously enabled or disabled. Note: URI\nvalues for archival states can't be changed once enabled.\n\n```\ntemporal operator namespace update \\\n    --namespace YourNamespaceName \\\n    --history-archival-state enabled \\\n    --visibility-archival-state disabled\n```"
+		s.Command.Long = "Update a Namespace using properties you specify.\n\n```\ntemporal operator namespace update [options]\n```\n\nAssign a Namespace's active Cluster (Service):\n\n```\ntemporal operator namespace update \\\n    --namespace YourNamespaceName \\\n    --active-cluster NewActiveCluster\n```\n\nActive Cluster changes cannot be combined with other Namespace updates.\nUpdate Namespace configuration, including the replication Cluster list,\nbefore changing the active Cluster in a separate command.\n\nPromote a Namespace for multi-region data replication:\n\n```\ntemporal operator namespace update \\\n    --namespace YourNamespaceName \\\n    --promote-global\n```\n\nYou may update archives that were previously enabled or disabled. Note: URI\nvalues for archival states can't be changed once enabled.\n\n```\ntemporal operator namespace update \\\n    --namespace YourNamespaceName \\\n    --history-archival-state enabled \\\n    --visibility-archival-state disabled\n```"
 	}
 	s.Command.Args = cobra.MaximumNArgs(1)
-	s.Command.Flags().StringVar(&s.ActiveCluster, "active-cluster", "", "Active Cluster (Service) name.")
+	s.Command.Flags().StringVar(&s.ActiveCluster, "active-cluster", "", "Active Cluster (Service) name. Cannot be combined with options that modify Namespace configuration.")
 	s.Command.Flags().StringArrayVar(&s.Cluster, "cluster", nil, "Cluster (Service) names.")
 	s.Command.Flags().StringArrayVar(&s.Data, "data", nil, "Namespace data as `KEY=VALUE` pairs. Keys must be identifiers, and values must be JSON values. For example: `YourKey={\"your\": \"value\"}` Can be passed multiple times.")
 	s.Command.Flags().StringVar(&s.Description, "description", "", "Namespace description.")
diff --git a/internal/temporalcli/commands.operator_namespace.go b/internal/temporalcli/commands.operator_namespace.go
index ca4b6c6d5..caf2bc0d0 100644
--- a/internal/temporalcli/commands.operator_namespace.go
+++ b/internal/temporalcli/commands.operator_namespace.go
@@ -2,6 +2,7 @@ package temporalcli
 
 import (
 	"fmt"
+	"strings"
 
 	"github.com/fatih/color"
 	"github.com/temporalio/cli/internal/printer"
@@ -193,6 +194,10 @@ func (c *TemporalOperatorNamespaceListCommand) run(cctx *CommandContext, args []
 }
 
 func (c *TemporalOperatorNamespaceUpdateCommand) run(cctx *CommandContext, args []string) error {
+	if err := c.validateFlags(); err != nil {
+		return err
+	}
+
 	cl, err := dialClient(cctx, &c.Parent.Parent.ClientOptions)
 	if err != nil {
 		return err
@@ -206,10 +211,6 @@ func (c *TemporalOperatorNamespaceUpdateCommand) run(cctx *CommandContext, args
 
 	var updateRequest *workflowservice.UpdateNamespaceRequest
 
-	if c.PromoteGlobal && len(c.ActiveCluster) > 0 {
-		return fmt.Errorf("both --promote-global and --active-cluster flags cannot be set together")
-	}
-
 	if c.PromoteGlobal {
 		cctx.Printer.Printlnf("Will promote local namespace to global namespace for:%s, other flag will be omitted. "+
 			"If it is already global namespace, this will be no-op.\n", nsName)
@@ -218,7 +219,7 @@ func (c *TemporalOperatorNamespaceUpdateCommand) run(cctx *CommandContext, args
 			PromoteNamespace: true,
 		}
 	} else if len(c.ActiveCluster) > 0 {
-		cctx.Printer.Printlnf("Will set active cluster name to: %s, other flag will be omitted.\n", c.ActiveCluster)
+		cctx.Printer.Printlnf("Will set active cluster name to: %s.\n", c.ActiveCluster)
 		replicationConfig := &replication.NamespaceReplicationConfig{
 			ActiveClusterName: c.ActiveCluster,
 		}
@@ -304,6 +305,42 @@ func (c *TemporalOperatorNamespaceUpdateCommand) run(cctx *CommandContext, args
 	return nil
 }
 
+func (c *TemporalOperatorNamespaceUpdateCommand) validateFlags() error {
+	if len(c.ActiveCluster) == 0 {
+		return nil
+	}
+	if c.PromoteGlobal {
+		return fmt.Errorf("both --promote-global and --active-cluster flags cannot be set together")
+	}
+
+	incompatibleFlagNames := [...]string{
+		"cluster",
+		"data",
+		"description",
+		"email",
+		"history-archival-state",
+		"history-uri",
+		"replication-state",
+		"retention",
+		"visibility-archival-state",
+		"visibility-uri",
+	}
+	var incompatibleFlags []string
+	for _, flag := range incompatibleFlagNames {
+		if c.Command.Flags().Changed(flag) {
+			incompatibleFlags = append(incompatibleFlags, "--"+flag)
+		}
+	}
+	if len(incompatibleFlags) == 0 {
+		return nil
+	}
+
+	return fmt.Errorf(
+		"--active-cluster cannot be combined with %s; update namespace configuration before changing the active cluster",
+		strings.Join(incompatibleFlags, ", "),
+	)
+}
+
 func printNamespaceDescriptions(cctx *CommandContext, responses ...*workflowservice.DescribeNamespaceResponse) error {
 	namespaces := make([]map[string]any, len(responses))
 	for i, resp := range responses {
diff --git a/internal/temporalcli/commands.operator_namespace_test.go b/internal/temporalcli/commands.operator_namespace_test.go
index 261fe07a0..d3ed50d01 100644
--- a/internal/temporalcli/commands.operator_namespace_test.go
+++ b/internal/temporalcli/commands.operator_namespace_test.go
@@ -3,13 +3,71 @@ package temporalcli_test
 import (
 	"fmt"
 	"os"
+	"testing"
 	"time"
 
+	"github.com/stretchr/testify/require"
 	"github.com/temporalio/cli/internal/temporalcli"
 	"go.temporal.io/api/enums/v1"
 	"go.temporal.io/api/workflowservice/v1"
 )
 
+func TestNamespaceUpdate_ActiveClusterRejectsOtherUpdates(t *testing.T) {
+	tests := []struct {
+		name      string
+		args      []string
+		wantError string
+	}{
+		{name: "cluster", args: []string{"--cluster", "cluster-a"}, wantError: "--active-cluster cannot be combined with --cluster"},
+		{name: "data", args: []string{"--data", "key=value"}, wantError: "--active-cluster cannot be combined with --data"},
+		{name: "description", args: []string{"--description", "description"}, wantError: "--active-cluster cannot be combined with --description"},
+		{name: "email", args: []string{"--email", "owner@example.com"}, wantError: "--active-cluster cannot be combined with --email"},
+		{name: "promote global", args: []string{"--promote-global"}, wantError: "both --promote-global and --active-cluster flags cannot be set together"},
+		{name: "history archival state", args: []string{"--history-archival-state", "enabled"}, wantError: "--active-cluster cannot be combined with --history-archival-state"},
+		{name: "history URI", args: []string{"--history-uri", "file:///tmp/history"}, wantError: "--active-cluster cannot be combined with --history-uri"},
+		{name: "replication state", args: []string{"--replication-state", "normal"}, wantError: "--active-cluster cannot be combined with --replication-state"},
+		{name: "retention", args: []string{"--retention", "24h"}, wantError: "--active-cluster cannot be combined with --retention"},
+		{name: "visibility archival state", args: []string{"--visibility-archival-state", "enabled"}, wantError: "--active-cluster cannot be combined with --visibility-archival-state"},
+		{name: "visibility URI", args: []string{"--visibility-uri", "file:///tmp/visibility"}, wantError: "--active-cluster cannot be combined with --visibility-uri"},
+	}
+
+	for _, output := range []string{"text", "json"} {
+		t.Run(output, func(t *testing.T) {
+			for _, test := range tests {
+				t.Run(test.name, func(t *testing.T) {
+					h := NewCommandHarness(t)
+					args := []string{
+						"operator", "namespace", "update",
+						"--address", "127.0.0.1:1",
+						"--namespace", "test-namespace",
+						"--active-cluster", "cluster-b",
+						"--output", output,
+					}
+					res := h.Execute(append(args, test.args...)...)
+
+					require.ErrorContains(t, res.Err, test.wantError)
+					require.Empty(t, res.Stdout.String())
+				})
+			}
+		})
+	}
+}
+
+func TestNamespaceUpdate_ActiveClusterReportsAllConflicts(t *testing.T) {
+	h := NewCommandHarness(t)
+	res := h.Execute(
+		"operator", "namespace", "update",
+		"--address", "127.0.0.1:1",
+		"--namespace", "test-namespace",
+		"--active-cluster", "cluster-b",
+		"--cluster", "cluster-a",
+		"--description", "description",
+	)
+
+	require.ErrorContains(t, res.Err, "--active-cluster cannot be combined with --cluster, --description")
+	require.Empty(t, res.Stdout.String())
+}
+
 func (s *SharedServerSuite) TestOperator_NamespaceCreateListAndDescribe() {
 	nsName := "test_namespace"
 	res := s.Execute(
@@ -107,6 +165,27 @@ func (s *SharedServerSuite) TestNamespaceUpdate() {
 	s.Equal("v3", describeResp.NamespaceInfo.Data["k3"])
 }
 
+func (s *SharedServerSuite) TestNamespaceUpdate_ActiveClusterAlone() {
+	nsName := "test-namespace-update-active-cluster"
+	res := s.Execute(
+		"operator", "namespace", "create",
+		"--address", s.Address(),
+		"--namespace", nsName,
+		"--global",
+		"--active-cluster", "active",
+		"--cluster", "active",
+	)
+	require.NoError(s.T(), res.Err)
+
+	res = s.Execute(
+		"operator", "namespace", "update",
+		"--address", s.Address(),
+		"--namespace", nsName,
+		"--active-cluster", "active",
+	)
+	require.NoError(s.T(), res.Err)
+}
+
 func (s *SharedServerSuite) TestNamespaceUpdate_NamespaceDontExist() {
 	nsName := "missing-namespace"
 	res := s.Execute(
diff --git a/internal/temporalcli/commands.yaml b/internal/temporalcli/commands.yaml
index 6d24a8a00..c360525fb 100644
--- a/internal/temporalcli/commands.yaml
+++ b/internal/temporalcli/commands.yaml
@@ -2694,6 +2694,10 @@ commands:
           --active-cluster NewActiveCluster
       ```
 
+      Active Cluster changes cannot be combined with other Namespace updates.
+      Update Namespace configuration, including the replication Cluster list,
+      before changing the active Cluster in a separate command.
+
       Promote a Namespace for multi-region data replication:
 
       ```
@@ -2715,7 +2719,9 @@ commands:
     options:
       - name: active-cluster
         type: string
-        description: Active Cluster (Service) name.
+        description: |
+          Active Cluster (Service) name.
+          Cannot be combined with options that modify Namespace configuration.
       - name: cluster
         type: string[]
         description: Cluster (Service) names.