diff --git a/pkg/cloudcommon/cronman/cronman.go b/pkg/cloudcommon/cronman/cronman.go
index b2e443d983..1dba9a33b2 100644
--- a/pkg/cloudcommon/cronman/cronman.go
+++ b/pkg/cloudcommon/cronman/cronman.go
@@ -1,33 +1,34 @@
 package cronman
 
 import (
-	"time"
-	"runtime/debug"
 	"context"
+	"reflect"
+	"runtime"
+	"runtime/debug"
+	"time"
 
 	"yunion.io/x/log"
 
+	"yunion.io/x/onecloud/pkg/appctx"
 	"yunion.io/x/onecloud/pkg/mcclient"
 	"yunion.io/x/onecloud/pkg/mcclient/auth"
-	"reflect"
-	"runtime"
 )
 
 const (
-	DEFAULT_CRON_INTERVAL = 60*time.Second // default resolution is 1 monutes
+	DEFAULT_CRON_INTERVAL = 60 * time.Second // default resolution is 1 monutes
 )
 
 type SCronJobManager struct {
 	checkInterval time.Duration
-	timer *time.Timer
-	jobs []SCronJob
+	timer         *time.Timer
+	jobs          []SCronJob
 }
 
 type SCronJob struct {
-	name string
+	name        string
 	runInterval time.Duration
-	job func(ctx context.Context, userCred mcclient.TokenCredential)
-	lastRun time.Time
+	job         func(ctx context.Context, userCred mcclient.TokenCredential)
+	lastRun     time.Time
 }
 
 func NewCronJobManager(interval time.Duration) *SCronJobManager {
@@ -89,7 +90,7 @@ func runJob(name string, job func(ctx context.Context, userCred mcclient.TokenCr
 	}()
 
 	ctx := context.Background()
+	ctx = context.WithValue(ctx, appctx.APP_CONTEXT_KEY_APPNAME, "Region-Corn-Service")
 	userCred := auth.AdminCredential()
 	job(ctx, userCred)
 }
-
diff --git a/pkg/cloudcommon/db/taskman/tasks.go b/pkg/cloudcommon/db/taskman/tasks.go
index bd8578ca36..8e4f45acf6 100644
--- a/pkg/cloudcommon/db/taskman/tasks.go
+++ b/pkg/cloudcommon/db/taskman/tasks.go
@@ -246,17 +246,21 @@ func (manager *STaskManager) NewParallelTask(ctx context.Context, taskName strin
 }
 
 func (manager *STaskManager) fetchTask(idStr string) *STask {
-	task, err := db.NewModelObject(manager)
+	iTask, err := db.NewModelObject(manager)
 	if err != nil {
 		log.Errorf("New task object fail: %s", err)
 		return nil
 	}
-	err = manager.Query().Equals("id", idStr).First(task)
+	err = manager.Query().Equals("id", idStr).First(iTask)
 	if err != nil {
 		log.Errorf("GetTask %s fail: %s", idStr, err)
 		return nil
 	}
-	return task.(*STask)
+	task := iTask.(*STask)
+	if task.Params == nil {
+		task.Params = jsonutils.NewDict()
+	}
+	return task
 }
 
 func (manager *STaskManager) execTask(taskId string, data jsonutils.JSONObject) {
@@ -412,9 +416,11 @@ func (self *STask) GetParentTask() *STask {
 
 func (self *STask) GetRequestContext() appctx.AppContextData {
 	ctxData := appctx.AppContextData{}
-	ctxJson, _ := self.Params.Get(REQUEST_CONTEXT_KEY)
-	if ctxJson != nil {
-		ctxJson.Unmarshal(&ctxData)
+	if self.Params != nil {
+		ctxJson, _ := self.Params.Get(REQUEST_CONTEXT_KEY)
+		if ctxJson != nil {
+			ctxJson.Unmarshal(&ctxData)
+		}
 	}
 	return ctxData
 }
diff --git a/pkg/compute/models/guests.go b/pkg/compute/models/guests.go
index c12f0e4221..20f695e286 100644
--- a/pkg/compute/models/guests.go
+++ b/pkg/compute/models/guests.go
@@ -2581,9 +2581,9 @@ func (self *SGuest) AllowDeleteItem(ctx context.Context, userCred mcclient.Token
 func (self *SGuest) CustomizeDelete(ctx context.Context, userCred mcclient.TokenCredential, query jsonutils.JSONObject, data jsonutils.JSONObject) error {
 	overridePendingDelete := false
 	purge := false
-	if data != nil {
-		overridePendingDelete = jsonutils.QueryBoolean(data, "override_pending_delete", false)
-		purge = jsonutils.QueryBoolean(data, "purge", false)
+	if query != nil {
+		overridePendingDelete = jsonutils.QueryBoolean(query, "override_pending_delete", false)
+		purge = jsonutils.QueryBoolean(query, "purge", false)
 	}
 	return self.StartDeleteGuestTask(ctx, userCred, "", purge, overridePendingDelete)
 }
diff --git a/pkg/compute/tasks/guest_rebuild_root_task.go b/pkg/compute/tasks/guest_rebuild_root_task.go
index 0d0ee7ee6a..03345b85ac 100644
--- a/pkg/compute/tasks/guest_rebuild_root_task.go
+++ b/pkg/compute/tasks/guest_rebuild_root_task.go
@@ -32,6 +32,10 @@ func (self *GuestRebuildRootTask) OnInit(ctx context.Context, obj db.IStandalone
 	}
 }
 
+func (self *GuestRebuildRootTask) OnStopServerComplete(ctx context.Context, guest *models.SGuest, data jsonutils.JSONObject) {
+	self.StartRebuildRootDisk(ctx, guest)
+}
+
 func (self *GuestRebuildRootTask) StartRebuildRootDisk(ctx context.Context, guest *models.SGuest) {
 	db.OpsLog.LogEvent(guest, db.ACT_REBUILDING_ROOT, nil, self.UserCred)
 	gds := guest.CategorizeDisks()