diff --git a/client/client.go b/client/client.go
index fb8c09ca..d5e6d25d 100644
--- a/client/client.go
+++ b/client/client.go
@@ -151,7 +151,8 @@ func NewClientMd5(uin int64, passwordMd5 [16]byte) *QQClient {
 			"ProfileService.Pb.ReqSystemMsgNew.Friend":                 decodeSystemMsgFriendPacket,
 			"MultiMsg.ApplyUp":                                         decodeMultiApplyUpResponse,
 			"MultiMsg.ApplyDown":                                       decodeMultiApplyDownResponse,
-			"OidbSvc.0x6d6_2":                                          decodeOIDB6d6Response,
+			"OidbSvc.0x6d6_2":                                          decodeOIDB6d62Response,
+			"OidbSvc.0x6d6_3":                                          decodeOIDB6d63Response,
 			"OidbSvc.0x6d8_1":                                          decodeOIDB6d81Response,
 			"OidbSvc.0x88d_0":                                          decodeGroupInfoResponse,
 			"OidbSvc.0xe07_0":                                          decodeImageOcrResponse,
@@ -641,17 +642,19 @@ func (c *QQClient) uploadPrivateImage(target int64, img []byte, count int) (*mes
 	count++
 	h := md5.Sum(img)
 	e, err := c.QueryFriendImage(target, h[:], int32(len(img)))
-	if err != nil {
+	if err == ErrNotExists {
 		// use group highway upload and query again for image id.
 		if _, err = c.UploadGroupImage(target, img); err != nil {
 			return nil, err
 		}
-		// safe
 		if count >= 5 {
-			return nil, errors.New("upload failed")
+			return e, nil
 		}
 		return c.uploadPrivateImage(target, img, count)
 	}
+	if err != nil {
+		return nil, err
+	}
 	return e, nil
 }
 
@@ -698,7 +701,10 @@ func (c *QQClient) QueryFriendImage(target int64, hash []byte, size int32) (*mes
 		return nil, errors.New(rsp.Message)
 	}
 	if !rsp.IsExists {
-		return nil, errors.New("image not exists")
+		return &message.FriendImageElement{
+			ImageId: rsp.ResourceId,
+			Md5:     hash,
+		}, ErrNotExists
 	}
 	return &message.FriendImageElement{
 		ImageId: rsp.ResourceId,
@@ -1124,6 +1130,7 @@ func (c *QQClient) doHeartbeat() {
 			_ = c.Conn.Close()
 		}
 		time.AfterFunc(30*time.Second, c.doHeartbeat)
+		return
 	}
 	c.heartbeatEnabled = false
 }
diff --git a/client/entities.go b/client/entities.go
index 172c6e83..d46743e1 100644
--- a/client/entities.go
+++ b/client/entities.go
@@ -11,6 +11,7 @@ import (
 var (
 	ErrAlreadyOnline  = errors.New("already online")
 	ErrMemberNotFound = errors.New("member not found")
+	ErrNotExists      = errors.New("not exists")
 )
 
 type (
diff --git a/client/group_file.go b/client/group_file.go
index 2b722880..fe873408 100644
--- a/client/group_file.go
+++ b/client/group_file.go
@@ -142,6 +142,16 @@ func (fs *GroupFileSystem) GetDownloadUrl(file *GroupFile) string {
 	return fs.client.GetGroupFileUrl(file.GroupCode, file.FileId, file.BusId)
 }
 
+// DeleteFile 删除群文件，需要管理权限.
+// 返回错误, 空为删除成功
+func (fs *GroupFileSystem) DeleteFile(parentFolderId, fileId string, busId int32) string {
+	i, err := fs.client.sendAndWait(fs.client.buildGroupFileDeleteReqPacket(fs.GroupCode, parentFolderId, fileId, busId))
+	if err != nil {
+		return err.Error()
+	}
+	return i.(string)
+}
+
 // OidbSvc.0x6d8_1
 func (c *QQClient) buildGroupFileListRequestPacket(groupCode int64, folderId string, startIndex uint32) (uint16, []byte) {
 	seq := c.nextSeq()
@@ -229,6 +239,27 @@ func (c *QQClient) buildGroupFileDownloadReqPacket(groupCode int64, fileId strin
 	return seq, packet
 }
 
+func (c *QQClient) buildGroupFileDeleteReqPacket(groupCode int64, parentFolderId, fileId string, busId int32) (uint16, []byte) {
+	seq := c.nextSeq()
+	body := &oidb.D6D6ReqBody{DeleteFileReq: &oidb.DeleteFileReqBody{
+		GroupCode:      groupCode,
+		AppId:          3,
+		BusId:          busId,
+		ParentFolderId: parentFolderId,
+		FileId:         fileId,
+	}}
+	b, _ := proto.Marshal(body)
+	req := &oidb.OIDBSSOPkg{
+		Command:       1750,
+		ServiceType:   3,
+		Bodybuffer:    b,
+		ClientVersion: "android 8.4.8",
+	}
+	payload, _ := proto.Marshal(req)
+	packet := packets.BuildUniPacket(c.Uin, seq, "OidbSvc.0x6d6_3", 1, c.OutGoingPacketSessionId, EmptyBytes, c.sigInfo.d2Key, payload)
+	return seq, packet
+}
+
 func decodeOIDB6d81Response(c *QQClient, _ uint16, payload []byte) (interface{}, error) {
 	pkg := oidb.OIDBSSOPkg{}
 	rsp := oidb.D6D8RspBody{}
@@ -242,7 +273,7 @@ func decodeOIDB6d81Response(c *QQClient, _ uint16, payload []byte) (interface{},
 }
 
 // OidbSvc.0x6d6_2
-func decodeOIDB6d6Response(_ *QQClient, _ uint16, payload []byte) (interface{}, error) {
+func decodeOIDB6d62Response(_ *QQClient, _ uint16, payload []byte) (interface{}, error) {
 	pkg := oidb.OIDBSSOPkg{}
 	rsp := oidb.D6D6RspBody{}
 	if err := proto.Unmarshal(payload, &pkg); err != nil {
@@ -251,7 +282,25 @@ func decodeOIDB6d6Response(_ *QQClient, _ uint16, payload []byte) (interface{},
 	if err := proto.Unmarshal(pkg.Bodybuffer, &rsp); err != nil {
 		return nil, err
 	}
+	if rsp.DownloadFileRsp.DownloadUrl == nil {
+		return nil, errors.New(rsp.DownloadFileRsp.ClientWording)
+	}
 	ip := rsp.DownloadFileRsp.DownloadIp
 	url := hex.EncodeToString(rsp.DownloadFileRsp.DownloadUrl)
 	return fmt.Sprintf("http://%s/ftn_handler/%s/", ip, url), nil
 }
+
+func decodeOIDB6d63Response(_ *QQClient, _ uint16, payload []byte) (interface{}, error) {
+	pkg := oidb.OIDBSSOPkg{}
+	rsp := oidb.D6D6RspBody{}
+	if err := proto.Unmarshal(payload, &pkg); err != nil {
+		return nil, err
+	}
+	if err := proto.Unmarshal(pkg.Bodybuffer, &rsp); err != nil {
+		return nil, err
+	}
+	if rsp.DeleteFileRsp == nil {
+		return "", nil
+	}
+	return rsp.DeleteFileRsp.ClientWording, nil
+}
diff --git a/message/message.go b/message/message.go
index 7d71b1d2..00392a9a 100644
--- a/message/message.go
+++ b/message/message.go
@@ -366,16 +366,16 @@ func ParseMessageElems(elems []*msg.Elem) []IMessageElement {
 			}
 		}
 		if elem.LightApp != nil && len(elem.LightApp.Data) > 1 {
-			var content string
+			var content []byte
 			if elem.LightApp.Data[0] == 0 {
-				content = string(elem.LightApp.Data[1:])
+				content = elem.LightApp.Data[1:]
 			}
 			if elem.LightApp.Data[0] == 1 {
-				content = string(binary.ZlibUncompress(elem.LightApp.Data[1:]))
+				content = binary.ZlibUncompress(elem.LightApp.Data[1:])
 			}
-			if content != "" {
+			if len(content) > 0 && len(content) < 1024*1024*1024 { // 解析出错 or 非法内容
 				// TODO: 解析具体的APP
-				return append(res, &LightAppElement{Content: content})
+				return append(res, &LightAppElement{Content: string(content)})
 			}
 		}
 		if elem.VideoFile != nil {