调用云函数失败，-404011 permission denied, open '/var/user

错误信息：

Error: cloud.callFunction:fail -404011 cloud function execution error. 云函数执行错误
云端堆栈信息(error stack)(requestId 11024889-de09-11eb-a0a6-52540096f86f, callid 1625541608169-0.6493597940355504):
Error: EACCES: permission denied, open '/var/user/index.js'
    at Object.openSync (:61480/appservice/fs.js:438)
    at Object.readFileSync (:61480/appservice/fs.js:343)
    at Object.Module._extensions..js (:61480/appservice/internal/modules/cjs/loader.js:711)
    at Module.load (:61480/appservice/internal/modules/cjs/loader.js:600)
    at tryModuleLoad (:61480/appservice/internal/modules/cjs/loader.js:539)
    at Function.Module._load (:61480/appservice/internal/modules/cjs/loader.js:531)
    at Module.require (:61480/appservice/internal/modules/cjs/loader.js:637)
    at require (:61480/appservice/internal/modules/cjs/helpers.js:22)
    at Object.module.exports.load (:61480/var/runtime/node10/UserFunction.js:27)
    at Runtime.handleOnce (:61480/var/runtime/node10/Runtime.engine.js:97)(env: macOS,mp,1.05.2106300; lib: 2.17.0)

云函数代码：

// 云函数入口文件
const cloud = require('wx-server-sdk')

cloud.init()

// 云函数入口函数
exports.main = async (event, context) => {
  const wxContext = cloud.getWXContext()

  return {
    event,
    openid: wxContext.OPENID,
    appid: wxContext.APPID,
    unionid: wxContext.UNIONID,
  }
}

云函数上传成功、部署成功，而且云函数和云开发环境的权限全都已经放开，允许所有用户访问。请问为什么还是会出现Permission denied错误呢？