diff --git a/plugin/scheduler_example/evict_leader.go b/plugin/scheduler_example/evict_leader.go
index b40633dfb2e..98c0abcfa25 100644
--- a/plugin/scheduler_example/evict_leader.go
+++ b/plugin/scheduler_example/evict_leader.go
@@ -260,7 +260,7 @@ func (handler *evictLeaderHandler) UpdateConfig(w http.ResponseWriter, r *http.R
 		id = (uint64)(idFloat)
 		if _, exists = handler.config.StoreIDWitRanges[id]; !exists {
 			if err := handler.config.cluster.BlockStore(id); err != nil {
-				handler.rd.JSON(w, http.StatusInternalServerError, err)
+				handler.rd.JSON(w, http.StatusInternalServerError, err.Error())
 				return
 			}
 		}
@@ -277,7 +277,7 @@ func (handler *evictLeaderHandler) UpdateConfig(w http.ResponseWriter, r *http.R
 	handler.config.BuildWithArgs(args)
 	err := handler.config.Persist()
 	if err != nil {
-		handler.rd.JSON(w, http.StatusInternalServerError, err)
+		handler.rd.JSON(w, http.StatusInternalServerError, err.Error())
 	}
 	handler.rd.JSON(w, http.StatusOK, nil)
 }
@@ -314,7 +314,7 @@ func (handler *evictLeaderHandler) DeleteConfig(w http.ResponseWriter, r *http.R
 		return
 	}
 
-	handler.rd.JSON(w, http.StatusInternalServerError, errors.New("the config does not exist"))
+	handler.rd.JSON(w, http.StatusInternalServerError, errors.New("the config does not exist").Error())
 }
 
 func newEvictLeaderHandler(config *evictLeaderSchedulerConfig) http.Handler {
diff --git a/server/schedulers/evict_leader.go b/server/schedulers/evict_leader.go
index de3028caee5..88d5cb0c516 100644
--- a/server/schedulers/evict_leader.go
+++ b/server/schedulers/evict_leader.go
@@ -299,7 +299,7 @@ func (handler *evictLeaderHandler) UpdateConfig(w http.ResponseWriter, r *http.R
 		id = (uint64)(idFloat)
 		if _, exists = handler.config.StoreIDWithRanges[id]; !exists {
 			if err := handler.config.cluster.BlockStore(id); err != nil {
-				handler.rd.JSON(w, http.StatusInternalServerError, err)
+				handler.rd.JSON(w, http.StatusInternalServerError, err.Error())
 				return
 			}
 		}
@@ -316,7 +316,7 @@ func (handler *evictLeaderHandler) UpdateConfig(w http.ResponseWriter, r *http.R
 	handler.config.BuildWithArgs(args)
 	err := handler.config.Persist()
 	if err != nil {
-		handler.rd.JSON(w, http.StatusInternalServerError, err)
+		handler.rd.JSON(w, http.StatusInternalServerError, err.Error())
 		return
 	}
 	handler.rd.JSON(w, http.StatusOK, nil)
@@ -340,15 +340,15 @@ func (handler *evictLeaderHandler) DeleteConfig(w http.ResponseWriter, r *http.R
 	if succ {
 		err = handler.config.Persist()
 		if err != nil {
-			handler.rd.JSON(w, http.StatusInternalServerError, err)
+			handler.rd.JSON(w, http.StatusInternalServerError, err.Error())
 			return
 		}
 		if last {
 			if err := handler.config.cluster.RemoveScheduler(EvictLeaderName); err != nil {
 				if err == ErrSchedulerNotFound {
-					handler.rd.JSON(w, http.StatusNotFound, err)
+					handler.rd.JSON(w, http.StatusNotFound, err.Error())
 				} else {
-					handler.rd.JSON(w, http.StatusInternalServerError, err)
+					handler.rd.JSON(w, http.StatusInternalServerError, err.Error())
 				}
 				return
 			}
@@ -358,7 +358,7 @@ func (handler *evictLeaderHandler) DeleteConfig(w http.ResponseWriter, r *http.R
 		return
 	}
 
-	handler.rd.JSON(w, http.StatusNotFound, ErrScheduleConfigNotExist)
+	handler.rd.JSON(w, http.StatusNotFound, ErrScheduleConfigNotExist.Error())
 }
 
 func newEvictLeaderHandler(config *evictLeaderSchedulerConfig) http.Handler {
diff --git a/server/schedulers/grant_leader.go b/server/schedulers/grant_leader.go
index 30e117e6f3b..e8067163ecc 100644
--- a/server/schedulers/grant_leader.go
+++ b/server/schedulers/grant_leader.go
@@ -249,7 +249,7 @@ func (handler *grantLeaderHandler) UpdateConfig(w http.ResponseWriter, r *http.R
 		id = (uint64)(idFloat)
 		if _, exists = handler.config.StoreIDWithRanges[id]; !exists {
 			if err := handler.config.cluster.BlockStore(id); err != nil {
-				handler.rd.JSON(w, http.StatusInternalServerError, err)
+				handler.rd.JSON(w, http.StatusInternalServerError, err.Error())
 				return
 			}
 		}
@@ -266,7 +266,7 @@ func (handler *grantLeaderHandler) UpdateConfig(w http.ResponseWriter, r *http.R
 	handler.config.BuildWithArgs(args)
 	err := handler.config.Persist()
 	if err != nil {
-		handler.rd.JSON(w, http.StatusInternalServerError, err)
+		handler.rd.JSON(w, http.StatusInternalServerError, err.Error())
 		return
 	}
 	handler.rd.JSON(w, http.StatusOK, nil)
@@ -290,15 +290,15 @@ func (handler *grantLeaderHandler) DeleteConfig(w http.ResponseWriter, r *http.R
 	if succ {
 		err = handler.config.Persist()
 		if err != nil {
-			handler.rd.JSON(w, http.StatusInternalServerError, err)
+			handler.rd.JSON(w, http.StatusInternalServerError, err.Error())
 			return
 		}
 		if last {
 			if err := handler.config.cluster.RemoveScheduler(GrantLeaderName); err != nil {
 				if err == ErrSchedulerNotFound {
-					handler.rd.JSON(w, http.StatusNotFound, err)
+					handler.rd.JSON(w, http.StatusNotFound, err.Error())
 				} else {
-					handler.rd.JSON(w, http.StatusInternalServerError, err)
+					handler.rd.JSON(w, http.StatusInternalServerError, err.Error())
 				}
 				return
 			}
@@ -308,7 +308,7 @@ func (handler *grantLeaderHandler) DeleteConfig(w http.ResponseWriter, r *http.R
 		return
 	}
 
-	handler.rd.JSON(w, http.StatusNotFound, ErrScheduleConfigNotExist)
+	handler.rd.JSON(w, http.StatusNotFound, ErrScheduleConfigNotExist.Error())
 }
 
 func newGrantLeaderHandler(config *grantLeaderSchedulerConfig) http.Handler {
diff --git a/server/schedulers/scatter_range.go b/server/schedulers/scatter_range.go
index ea08e5a00b0..f05a3b57600 100644
--- a/server/schedulers/scatter_range.go
+++ b/server/schedulers/scatter_range.go
@@ -237,7 +237,7 @@ func (handler *scatterRangeHandler) UpdateConfig(w http.ResponseWriter, r *http.
 	name, ok := input["range-name"].(string)
 	if ok {
 		if name != handler.config.GetRangeName() {
-			handler.rd.JSON(w, http.StatusInternalServerError, errors.New("Cannot change the range name, please delete this schedule"))
+			handler.rd.JSON(w, http.StatusInternalServerError, errors.New("Cannot change the range name, please delete this schedule").Error())
 			return
 		}
 		args = append(args, name)
@@ -261,7 +261,7 @@ func (handler *scatterRangeHandler) UpdateConfig(w http.ResponseWriter, r *http.
 	handler.config.BuildWithArgs(args)
 	err := handler.config.Persist()
 	if err != nil {
-		handler.rd.JSON(w, http.StatusInternalServerError, err)
+		handler.rd.JSON(w, http.StatusInternalServerError, err.Error())
 	}
 	handler.rd.JSON(w, http.StatusOK, nil)
 }