diff --git a/agent.go b/agent.go
index 8423435..e8e920a 100644
--- a/agent.go
+++ b/agent.go
@@ -283,7 +283,7 @@ func (ag *Agent) GetAction(api deepinfra.API, p model.Protocol, grp int64, role
 					logrus.Debugln("[goba] GetAction extract memory err:", err)
 					ag.AddResponse(grp, &APIResponse{
 						Status:  "error",
-						Data:    []byte(`""`),
+						Data:    []byte(`null`),
 						Message: err.Error(),
 					})
 					continue
@@ -300,7 +300,7 @@ func (ag *Agent) GetAction(api deepinfra.API, p model.Protocol, grp int64, role
 				logrus.Debugln("[goba] GetAction add memory response:", s, "msg:", msg)
 				ag.AddResponse(grp, &APIResponse{
 					Status:  s,
-					Data:    []byte(`""`),
+					Data:    []byte(`null`),
 					Message: msg,
 				})
 			}