Pm2: Error run .mjs file

[YuriyTigiev]

What's going wrong?

When I run pm2 start index.mjs -e logs/err.log I get an error

PS C:\Users\yuriy\Documents\Projects\testpm2> npm -v
6.13.6
PS C:\Users\yuriy\Documents\Projects\testpm2> node -v
v13.7.0

Error [ERR_REQUIRE_ESM] [ERR_REQUIRE_ESM]: Must use import to load ES Module: C:\Users\yuriy\Documents\Projects\testpm2\index.mjs
    at Module.load (internal/modules/cjs/loader.js:998:11)
    at Function.Module._load (internal/modules/cjs/loader.js:899:14)
    at Object.<anonymous> (C:\Users\yuriy\AppData\Roaming\npm\node_modules\pm2\lib\ProcessContainerFork.js:78:21)
    at Module._compile (internal/modules/cjs/loader.js:1151:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1171:10)
    at Module.load (internal/modules/cjs/loader.js:1000:32)
    at Function.Module._load (internal/modules/cjs/loader.js:899:14)
    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:71:12)
    at internal/main/run_main_module.js:17:47

index.mjs

import express from 'express';
const app = express();
const port = 3000;
app.listen(port, () => console.log(`App running on port  + ${port}`));

package.json

{
  "name": "testpm2",
  "version": "1.0.0",
  "engines": {
    "node": ">=13.0.0"
  },
  "description": "",
  "main": "index.mjs",
  "type": "module",
  "scripts": {},
  "repository": {
    "type": "git",
    "url": "git+https://github.com/YuriyTigiev/testpm2.git"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "bugs": {
    "url": "https://github.com/YuriyTigiev/testpm2/issues"
  },
  "homepage": "https://github.com/YuriyTigiev/testpm2#readme",
  "devDependencies": {
    "cross-env": "^6.0.3",
    "eslint": "^6.8.0",
    "eslint-config-standard": "^14.1.0",
    "eslint-plugin-import": "^2.20.0",
    "eslint-plugin-node": "^11.0.0",
    "eslint-plugin-promise": "^4.2.1",
    "eslint-plugin-standard": "^4.0.1"
  },
  "dependencies": {
    "dotenv": "^8.2.0",
    "express": "^4.17.1",
    "module-js": "^7.0.1"
  }
}

ecosystem.config.mjs

export const apps = [
  {
    name: 'myapp',
    script: './index.mjs',
    watch: true,
    env: {
      'PORT': 3000,
      'NODE_ENV': 'development'
    }
  }
];

How could we reproduce this issue?

$ pm2 report
pm2 report doesn't work on windows 10 

[Unitech]

Which pm2 version?

[YuriyTigiev]

2.9.2-next

[Unitech]

upgrade to latest

npm install pm2@latest -g
pm2 update

it will works

[YuriyTigiev]

I did as you wrote and now I got another error

After run the script every a few seconds appears two dos screens and they hide immediately and it happens constantly until I stop the script by a command.

pm2 start index.mjs -e logs/err.log

pm2 stop 0

pm2 --version 
4.2.3

(node:8776) ExperimentalWarning: The ESM module loader is experimental.
Error [ERR_UNSUPPORTED_ESM_URL_SCHEME]: Only file and data URLs are supported by the default ESM loader
    at Loader.defaultResolve [as _resolve] (internal/modules/esm/resolve.js:33:11)
    at Loader.resolve (internal/modules/esm/loader.js:85:40)
    at Loader.getModuleJob (internal/modules/esm/loader.js:188:40)
    at Loader.import (internal/modules/esm/loader.js:163:28)
    at importModuleDynamically (internal/modules/cjs/loader.js:1094:27)
    at exports.importModuleDynamicallyCallback (internal/process/esm_loader.js:37:14)
    at Object.<anonymous> (C:\Users\yuriy\AppData\Roaming\npm\node_modules\pm2\lib\ProcessContainerFork.js:29:24)
    at Module._compile (internal/modules/cjs/loader.js:1151:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1171:10)
    at Module.load (internal/modules/cjs/loader.js:1000:32) {
  code: 'ERR_UNSUPPORTED_ESM_URL_SCHEME'
}

[Unitech]

Could you share me a sample app so I can try this

[YuriyTigiev]

This is a test project for testing pm2.

testpm2.zip

[YuriyTigiev]

Any updates?

[AndrewIsh]

I'm also seeing this, although I'm using Node 12.16.1 (LTS) which doesn't require the .mjs extension. I have { type: "module" } in my package.json, I believe my ecosystem.config.js is correct:

export default {
    apps: [
        {
            name: 'ems-api',
            script: 'app.js',
            instances: 1,
            autorestart: true,
            watch: true,
            max_memory_restart: '1G',
            env: {
                NODE_ENV: 'development'
            },
            env_production: {
                NODE_ENV: 'production'
            }
        }
    ]
};

and the error:

[PM2][ERROR] File ecosystem.config.js malformated
Error [ERR_REQUIRE_ESM]: Must use import to load ES Module: /home/ems/ems-api/ecosystem.config.js            
require() of ES modules is not supported.
require() of /home/ems/ems-api/ecosystem.config.js from /usr/lib/node_modules/pm2/lib/Common.js is an ES module file as it is a .js file whose nearest parent package.json contains "type": "module" which defines all .js files in that package scope as ES modules.
Instead rename ecosystem.config.js to end in .cjs, change the requiring code to use import(), or remove "type": "module" from /home/ems/ems-api/package.json.
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1174:13)                                
    at Module.load (internal/modules/cjs/loader.js:1002:32)                                                  
    at Function.Module._load (internal/modules/cjs/loader.js:901:14)     export default {
    apps: [
        {
            name: 'ems-api',
            script: 'app.js',
            instances: 1,
            autorestart: true,
            watch: true,
            max_memory_restart: '1G',
            env: {
                NODE_ENV: 'development'
            },
            env_production: {
                NODE_ENV: 'production'
            }
        }
    ]
};                                    
    at Module.require (internal/modules/cjs/loader.js:1044:19)                                               
    at require (internal/modules/cjs/helpers.js:77:18)
    at Object.Common.parseConfig (/usr/lib/node_modules/pm2/lib/Common.js:289:12)                            
    at API._startJson (/usr/lib/node_modules/pm2/lib/API.js:957:25)                                          
    at API.start (/usr/lib/node_modules/pm2/lib/API.js:333:12)                                               
    at /usr/lib/node_modules/pm2/lib/binaries/CLI.js:286:13                                                  
    at /usr/lib/node_modules/pm2/node_modules/async/internal/withoutIndex.js:8:40 {                          
  code: 'ERR_REQUIRE_ESM'
}

[tnokin]

I had to patch pm2 v4.4 on my PC to solve this - issue is that path.resolve() returns "c:..." on Windows, and the ESM "import" does not accepts it. I had to patch pm2libProcessContainer.js with this (discusting) code:
if (ProcessUtils.isESModule(script) === true) {
let x = process.env.pm_exec_path;
if (x.startsWith("c:")) x = x.substring(2);
x = x.replace(/\/g, "/");
import(x);
If anyone has a better solution...

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[chrisstone07]

@AndrewIsh I'm facing the same issue, have you got this issue fixed?

[AndrewIsh]

@AndrewIsh I'm facing the same issue, have you got this issue fixed?

I ended up side stepping the whole thing by switching from import to require

[chrisstone07]

Oh well, that's definitely not an option for me :( Hope someone can get mjs to work on node 12.18 and pm2 4.4.0.

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[MastroBoy]

@tnokin thanks, I had to change your code a little to this in pm2libProcessContainer.js

if (ProcessUtils.isESModule(script) === true){
let x = process.env.pm_exec_path;
if (x.startsWith("C:",0)){
x = x.substring(2);
let pathSep = '\'; <- double slash not one
x = x.replace(new RegExp('\' + pathSep, 'g'), '/'); <- double slash not one
}
import(x);
//import(process.env.pm_exec_path); <-- commented out
}else{
require('module')._load(script, null, true);
}

[clshortfuse]

I'm guessing PM2 doesn't support ESM on Windows. For those in a pinch, https://github.com/coreybutler/node-windows after you install it as a service.

[kostadinSpiridonov]

Is there a plan for fixing this issue at all since we are experiencing the same behavior?

[Smilebags]

Sad this isn't supported. It'd be really nice to be able to use standard Node features in apps even when running through pm2.

[SammyWhamy]

I also had the same issue, the workaround I found is to use
pm2 start node -- .
This way pm2 starts up node which starts your app. In my case I use . (Starts the main: entry in package.json), but I'm sure you can also use pm2 start node -- server.js or pm2 start npm -- start (I haven't tried these, but I don't see why they wouldn't work).

I run a discord bot and for some reason if I add --watch it restarts my bot every time I do a command, this might be a side effect from using this work around. Although I can't be sure since I can't get my bot to run with pm2 start server.js.

I've also tried to run pm2 start nodemon -- server.js as a workaround to the --watch issue but that throws a syntax error for:
@ECHO off in the nodemon package

[aa04753]

Thanks @SammyWhamy, that worked for me on Windows 10, node v14.8.0, pm2 v4.4.1

[microJ]

thanks @SammyWhamy , use pm2 start node -- app.js is worked。
but use node ./job/checkMongoDB.js && pm2 start node -- app.js doesn't work，it's confused 🤣