diff --git a/inputs/nginx_upstream_check/nginx_upstream_check.go b/inputs/nginx_upstream_check/nginx_upstream_check.go
index 53123a0f..59bc6b7f 100644
--- a/inputs/nginx_upstream_check/nginx_upstream_check.go
+++ b/inputs/nginx_upstream_check/nginx_upstream_check.go
@@ -2,7 +2,6 @@ package nginx_upstream_check
 
 import (
 	"encoding/json"
-	"errors"
 	"fmt"
 	"io"
 	"log"
@@ -113,7 +112,7 @@ func (ins *Instance) Init() error {
 	}
 
 	if len(ins.Targets) == 0 {
-		return errors.New("nginx_upstream_check targets empty")
+		return types.ErrInstancesEmpty
 	}
 
 	client, err := ins.createHTTPClient()
diff --git a/inputs/ntp/ntp.go b/inputs/ntp/ntp.go
index 99f32a6f..e44f44e4 100644
--- a/inputs/ntp/ntp.go
+++ b/inputs/ntp/ntp.go
@@ -1,12 +1,12 @@
 package ntp
 
 import (
-	"errors"
 	"log"
 	"time"
 
 	"flashcat.cloud/categraf/config"
 	"flashcat.cloud/categraf/inputs"
+	"flashcat.cloud/categraf/types"
 	"github.com/toolkits/pkg/container/list"
 	"github.com/toolkits/pkg/nux"
 )
@@ -33,7 +33,7 @@ func (n *NTPStat) Drop() {}
 
 func (n *NTPStat) Init() error {
 	if len(n.NTPServers) == 0 {
-		return errors.New("ntp servers empty")
+		return types.ErrInstancesEmpty
 	}
 	return nil
 }