Firebase Functions模拟器启动报错：无法确定后端规格 求排查

启动Firebase Functions模拟器时，出现以下错误：

⬢ functions: Failed to load function definition from source: FirebaseError: User code failed to load. Cannot determine backend specification

此前该错误为间歇性出现，只能靠反复重启解决，如今已100%触发，完全阻塞开发。经过数小时排查仍无头绪。

环境信息 #

firebase-tools版本：

$ firebase --version
13.17.0

最小复现代码 #

functions/index.js #

const admin = require("firebase-admin/app");
admin.initializeApp();

const functions = require("firebase-functions/v1");

exports.created = functions.auth.user().onCreate(async (user) => {
  const email = user.email;
  console.log(email);
  return;
});

functions/package.json #

{
  "name": "functions",
  "description": "Cloud Functions for Firebase",
  "scripts": {
    "lint": "eslint .",
    "serve": "firebase emulators:start --only functions",
    "shell": "firebase functions:shell",
    "start": "npm run shell",
    "deploy": "firebase deploy --only functions",
    "logs": "firebase functions:log"
  },
  "engines": {
    "node": "18"
  },
  "main": "index.js",
  "private": true,
  "dependencies": {
    "firebase-admin": "^12.4.0",
    "firebase-functions": "^6.0.1",
    "nodemailer": "^6.9.15"
  }
}

Debug日志（错误前内容） #

Failed to find version of module node: reached end of search path src/functions/node_modules
✔  functions: Using node@18 from host. 
Could not find functions.yaml. Must use http discovery
Found firebase-functions binary at 'src/functions/node_modules/.bin/firebase-functions'
Serving at port 8872

⬢  functions: Failed to load function definition from source: FirebaseError: User code failed to load. Cannot determine backend specification

调试更新 #

进一步调试发现，模拟器启动时会执行以下命令加载函数代码：

node src/functions/node_modules/.bin/firebase-functions src/functions

目前猜测问题可能出在两个方向：

• firebase-tools不再生成functions.yaml（可能是旧版本遗留的兼容性问题）
• firebase-functions的Node进程崩溃，导致无法在firebase-tools预期的10秒超时内返回函数代码信息

内容的提问来源于stack exchange，提问作者cmjordan