开发者工具和真机测试没有遇到过，但是线上小程序的错误日志分析里，有大量使用2.16基础库的用户这个接口都获取不到UpdateManager这个对象

onLaunch: function (e) {
// 获取更新实例
    const updateManager = wx.getUpdateManager()
    updateManager.onCheckForUpdate(function (res) {
      // 请求完新版本信息的回调
      console.log(res.hasUpdate)
    })
    // 更新提示
    updateManager.onUpdateReady(function () {
      wx.showModal({
        title: '更新提示',
        content: '新版本已经准备好，是否重启应用？',
        success: function (res) {
          if (res.confirm) {
            updateManager.applyUpdate()
          }
        }
      })
    })
    // 更新失败
    updateManager.onUpdateFailed(function () {
      wx.showToast({
        title: '新版本下载失败，请重启应用',
        icon: 'none'
      })
    })
}

因为错误日志都出现在updateManager.onCheckForUpdate，基本可以断定是冷启动时wx.getUpdateManager()偶现失效，错误日志如下：

/**
 * Andorid
 * 客户端版本号
 * 8.0.2	86.67%
 * 8.0.1	13.33%
 * 基础库2.16.0      100%
 * 
**/

  Cannot read property \'onCheckForUpdate\' of undefined
  
  TypeError: Cannot read property \'onCheckForUpdate\' of undefined
  
  at Oe.checkAppUpdate (https://app.js:35:19)
  
  at Oe.<anonymous> (https://lib/WASubContext.js:2:2386798)
  
  at Oe.onLaunch (https://app.js:14:10)
  
  at Oe.<anonymous> (https://lib/WASubContext.js:2:2387256)
  
  at new Oe (https://lib/WASubContext.js:2:2388013)
  
  at Function.<anonymous> (https://lib/WASubContext.js:2:2388325)
  
  at https://lib/WASubContext.js:2:2374880
  
  at https://app.js:11:1
  
  at require (https://lib/WASubContext.js:2:2429539)
  
  at https://usr/app-service.js:5377:10
  
/**
 * iOS
 * 客户端版本号
 * 8.0.4        53.85%
 * 8.0.2        30.77%
 * 8.0.3        15.38%
 * 基础库版本2.16.0    100%
**/
  undefined is not an object (evaluating \'e.onCheckForUpdate\')
  
  checkAppUpdate@https://app.js:35:5
  
  https://lib/WASubContext.js:2:2386803
  
  onLaunch@https://app.js:14:10

  https://lib/WASubContext.js:2:2387261
  
  Oe@https://lib/WASubContext.js:2:2388021
  
  https://lib/WASubContext.js:2:2388331
  
  https://lib/WASubContext.js:2:2374885
  
  https://app.js:11:1
  
  require@https://lib/WASubContext.js:2:2429540
  
  global code@https://usr/app-service.js:5364:17
  
  value@https://lib/WAServiceMainContext.js:2:154041
  
  https://lib/WAServiceMainContext.js:2:157113
  
  https://lib/WAServiceMainContext.js:2:157080
  
  w@https://lib/WAServiceMainContext.js:2:82070
  
  s@https://lib/WAServiceMainContext.js:2:82344
  
  a@https://lib/WAServiceMainContext.js:2:156029
  
  https://lib/WAServiceMainContext.js:2:157540
  
  https://lib/WAServiceMainContext.js:2:146632
  
  https://lib/WAServiceMainContext.js:2:259690
  
  https://lib/WAServiceMainContext.js:2:258655
  
  https://lib/WAServiceMainContext.js:2:258619
  
  https://lib/WAServiceMainContext.js:2:259690
  
  w@https://lib/WAServiceMainContext.js:2:78332

现在只能先使用定时器延迟执行此段代码，看看是否能够去除小程序后台错误日志