startLocalServiceDiscovery在微信7.0.18上运行失败

今天升级了一下微信到7.0.18，以前运行OK的代码出问题了，就如下简单的代码，在开发工具上会到success里面，但在真机上就会到fail里面去。而且微信没有升级到7.0.18之前都运行的好好的。郁闷。错误信息就是：startLocalServiceDiscovery:fail search error

wx.startLocalServiceDiscovery({

      serviceType: '_http._tcp.',

      success: function(res){

        let items = that.data.items;

        items.push('success');

        items.push(res.errMsg)

        that.setData({items: items})

      },

      fail:function(res){

        let items = that.data.items;

        items.push('fail');

        items.push(res.errMsg)

        that.setData({items: items})

      },

      complete:function(res){

        let items = that.data.items;

        items.push('complete');

        items.push(res.errMsg)

        that.setData({items: items})

      },

    })

  },