diff --git a/client/errs/errno.go b/client/errs/errno.go
index a5fb453e4c0..0dbcb4fe147 100644
--- a/client/errs/errno.go
+++ b/client/errs/errno.go
@@ -25,7 +25,7 @@ const (
 	// NoLeaderErr indicates there is no leader in the cluster currently.
 	NoLeaderErr = "no leader"
 	// NotLeaderErr indicates the non-leader member received the requests which should be received by leader.
-	NotLeaderErr = "is not leader"
+	NotLeaderErr = "not leader"
 	// MismatchLeaderErr indicates the non-leader member received the requests which should be received by leader.
 	MismatchLeaderErr = "mismatch leader id"
 	// NotServedErr indicates an tso node/pod received the requests for the keyspace groups which are not served by it.
@@ -33,7 +33,7 @@ const (
 	// RetryTimeoutErr indicates the server is busy.
 	RetryTimeoutErr = "retry timeout"
 	// NotPrimaryErr indicates the non-primary member received the requests which should be received by primary.
-	NotPrimaryErr = "is not primary"
+	NotPrimaryErr = "not primary"
 )
 
 // client errors
diff --git a/client/errs/errs.go b/client/errs/errs.go
index 2c25e009849..da333efda4c 100644
--- a/client/errs/errs.go
+++ b/client/errs/errs.go
@@ -31,7 +31,8 @@ func IsLeaderChange(err error) bool {
 		return true
 	}
 	errMsg := err.Error()
-	return strings.Contains(errMsg, NotLeaderErr) ||
+	return strings.Contains(errMsg, NoLeaderErr) ||
+		strings.Contains(errMsg, NotLeaderErr) ||
 		strings.Contains(errMsg, MismatchLeaderErr) ||
 		strings.Contains(errMsg, NotServedErr) ||
 		strings.Contains(errMsg, NotPrimaryErr)
diff --git a/client/http/client.go b/client/http/client.go
index 161019713af..123ca616422 100644
--- a/client/http/client.go
+++ b/client/http/client.go
@@ -128,8 +128,8 @@ func (ci *clientInner) requestWithRetry(
 	)
 	execFunc := func() error {
 		defer func() {
-			// - If the status code is 503, it indicates that there may be PD leader/follower changes.
-			// - If the error message contains the leader/primary change information, it indicates that there may be PD leader/primary change.
+			// If the status code is 503, it indicates that there may be PD leader/follower changes.
+			// If the error message contains the leader/primary change information, it indicates that there may be PD leader/primary change.
 			if statusCode == http.StatusServiceUnavailable || errs.IsLeaderChange(err) {
 				ci.sd.ScheduleCheckMemberChanged()
 			}
@@ -243,6 +243,8 @@ func (ci *clientInner) doRequest(
 		if readErr != nil {
 			logFields = append(logFields, zap.NamedError("read-body-error", err))
 		} else {
+			// API server will return a JSON body containing the detailed error message
+			// when the status code is not `http.StatusOK` 200.
 			bs = bytes.TrimSpace(bs)
 			logFields = append(logFields, zap.ByteString("body", bs))
 		}
diff --git a/client/pd_service_discovery_test.go b/client/pd_service_discovery_test.go
index f4cde0e1911..44171873b1a 100644
--- a/client/pd_service_discovery_test.go
+++ b/client/pd_service_discovery_test.go
@@ -29,6 +29,7 @@ import (
 	"github.com/pingcap/kvproto/pkg/pdpb"
 	"github.com/stretchr/testify/require"
 	"github.com/stretchr/testify/suite"
+	"github.com/tikv/pd/client/errs"
 	"github.com/tikv/pd/client/grpcutil"
 	"github.com/tikv/pd/client/testutil"
 	"google.golang.org/grpc"
@@ -205,7 +206,7 @@ func (suite *serviceClientTestSuite) TestServiceClient() {
 	re.NotNil(leaderConn)
 
 	_, err := pb.NewGreeterClient(followerConn).SayHello(suite.ctx, &pb.HelloRequest{Name: "pd"})
-	re.ErrorContains(err, "not leader")
+	re.ErrorContains(err, errs.NotLeaderErr)
 	resp, err := pb.NewGreeterClient(leaderConn).SayHello(suite.ctx, &pb.HelloRequest{Name: "pd"})
 	re.NoError(err)
 	re.Equal("Hello pd", resp.GetMessage())
diff --git a/client/resource_manager_client.go b/client/resource_manager_client.go
index 872b241cfe7..98b123c0823 100644
--- a/client/resource_manager_client.go
+++ b/client/resource_manager_client.go
@@ -16,7 +16,6 @@ package pd
 
 import (
 	"context"
-	"strings"
 	"time"
 
 	"github.com/gogo/protobuf/proto"
@@ -35,10 +34,6 @@ const (
 	modify                     actionType = 1
 	groupSettingsPathPrefix               = "resource_group/settings"
 	controllerConfigPathPrefix            = "resource_group/controller"
-	// errNotPrimary is returned when the requested server is not primary.
-	errNotPrimary = "not primary"
-	// errNotLeader is returned when the requested server is not pd leader.
-	errNotLeader = "not leader"
 )
 
 // GroupSettingsPathPrefixBytes is used to watch or get resource groups.
@@ -83,7 +78,7 @@ func (c *client) resourceManagerClient() (rmpb.ResourceManagerClient, error) {
 
 // gRPCErrorHandler is used to handle the gRPC error returned by the resource manager service.
 func (c *client) gRPCErrorHandler(err error) {
-	if strings.Contains(err.Error(), errNotPrimary) || strings.Contains(err.Error(), errNotLeader) {
+	if errs.IsLeaderChange(err) {
 		c.pdSvcDiscovery.ScheduleCheckMemberChanged()
 	}
 }
diff --git a/errors.toml b/errors.toml
index a275cfa7501..a61c23a6fbd 100644
--- a/errors.toml
+++ b/errors.toml
@@ -16,6 +16,11 @@ error = '''
 redirect failed
 '''
 
+["PD:apiutil:ErrRedirectNoLeader"]
+error = '''
+redirect finds no leader
+'''
+
 ["PD:apiutil:ErrRedirectToNotLeader"]
 error = '''
 redirect to not leader
diff --git a/pkg/errs/errno.go b/pkg/errs/errno.go
index 8f67c59cfcc..1f56a821032 100644
--- a/pkg/errs/errno.go
+++ b/pkg/errs/errno.go
@@ -197,6 +197,7 @@ var (
 var (
 	ErrRedirect             = errors.Normalize("redirect failed", errors.RFCCodeText("PD:apiutil:ErrRedirect"))
 	ErrOptionNotExist       = errors.Normalize("the option %s does not exist", errors.RFCCodeText("PD:apiutil:ErrOptionNotExist"))
+	ErrRedirectNoLeader     = errors.Normalize("redirect finds no leader", errors.RFCCodeText("PD:apiutil:ErrRedirectNoLeader"))
 	ErrRedirectToNotLeader  = errors.Normalize("redirect to not leader", errors.RFCCodeText("PD:apiutil:ErrRedirectToNotLeader"))
 	ErrRedirectToNotPrimary = errors.Normalize("redirect to not primary", errors.RFCCodeText("PD:apiutil:ErrRedirectToNotPrimary"))
 )
diff --git a/pkg/utils/apiutil/serverapi/middleware.go b/pkg/utils/apiutil/serverapi/middleware.go
index 756ec571e6c..0718702b5a5 100755
--- a/pkg/utils/apiutil/serverapi/middleware.go
+++ b/pkg/utils/apiutil/serverapi/middleware.go
@@ -210,7 +210,7 @@ func (h *redirector) ServeHTTP(w http.ResponseWriter, r *http.Request, next http
 		leader := h.waitForLeader(r)
 		// The leader has not been elected yet.
 		if leader == nil {
-			http.Error(w, "no leader", http.StatusServiceUnavailable)
+			http.Error(w, errs.ErrRedirectNoLeader.FastGenByArgs().Error(), http.StatusServiceUnavailable)
 			return
 		}
 		// If the leader is the current server now, we can handle the request directly.
diff --git a/tests/integrations/mcs/tso/keyspace_group_manager_test.go b/tests/integrations/mcs/tso/keyspace_group_manager_test.go
index 25d9516bf63..6d861962d9b 100644
--- a/tests/integrations/mcs/tso/keyspace_group_manager_test.go
+++ b/tests/integrations/mcs/tso/keyspace_group_manager_test.go
@@ -28,6 +28,7 @@ import (
 	"github.com/stretchr/testify/require"
 	"github.com/stretchr/testify/suite"
 	pd "github.com/tikv/pd/client"
+	clierrs "github.com/tikv/pd/client/errs"
 	"github.com/tikv/pd/pkg/election"
 	"github.com/tikv/pd/pkg/errs"
 	mcsutils "github.com/tikv/pd/pkg/mcs/utils"
@@ -467,8 +468,8 @@ func (suite *tsoKeyspaceGroupManagerTestSuite) dispatchClient(
 				errMsg := err.Error()
 				// Ignore the errors caused by the split and context cancellation.
 				if strings.Contains(errMsg, "context canceled") ||
-					strings.Contains(errMsg, "not leader") ||
-					strings.Contains(errMsg, "not served") ||
+					strings.Contains(errMsg, clierrs.NotLeaderErr) ||
+					strings.Contains(errMsg, clierrs.NotServedErr) ||
 					strings.Contains(errMsg, "ErrKeyspaceNotAssigned") ||
 					strings.Contains(errMsg, "ErrKeyspaceGroupIsMerging") {
 					continue
diff --git a/tests/server/cluster/cluster_test.go b/tests/server/cluster/cluster_test.go
index 07bcf3ee2a1..9e70a52d11d 100644
--- a/tests/server/cluster/cluster_test.go
+++ b/tests/server/cluster/cluster_test.go
@@ -662,7 +662,7 @@ func TestNotLeader(t *testing.T) {
 	grpcStatus, ok := status.FromError(err)
 	re.True(ok)
 	re.Equal(codes.Unavailable, grpcStatus.Code())
-	re.Equal("not leader", grpcStatus.Message())
+	re.ErrorContains(server.ErrNotLeader, grpcStatus.Message())
 }
 
 func TestStoreVersionChange(t *testing.T) {