Guide Node.js App on CloudPanel Shows 502 or Keeps Restarting: PM2 Fixes

**JAY** · (This post was last modified: 10-23-2026, 09:37 AM by JAY.)

Node.js app on CloudPanel shows 502 or keeps restarting: PM2 fixes

Your Node.js site in CloudPanel shows 502 Bad Gateway, or it works for a while and then dies, or it's gone after every server reboot. For a Node.js site, CloudPanel's Nginx simply forwards visitors to your app on a local port. A 502 means Nginx knocked on that port and nobody answered. This guide shows how to find out why. Setting up a new app? See How to host a Node.js app on CloudPanel with PM2.

Step 1: Compare the ports
When you created the Node.js site, you entered an App Port (for example 3000). Nginx sends traffic to

Code:

127.0.0.1:3000

. Your app must listen on exactly that port. Check what's listening:

Code:

ss -tlnp | grep node

Nothing listed: the app isn't running. Go to Step 2.
Listening on another port (say 8080): change your app's port, or change the site's App Port in CloudPanel to match.
Listening on
Code:
::1
only, or on a specific external IP: make the app listen on
Code:
127.0.0.1
(or
Code:
0.0.0.0
). Many frameworks read
Code:
PORT
and
Code:
HOST
environment variables.

Step 2: Is PM2 running the app?
Log in as the site user (PM2 is per user, so root's PM2 list is a different one):

Code:

pm2 list

online: running. If you still get 502, recheck the port (Step 1).
errored or a high restart count (↺): the app crashes on start. Go to Step 3.
Empty list: the app was never started as this user, or PM2 lost it after a reboot (Step 4).

Step 3: Read the app's error log

Code:

pm2 logs --lines 50

The usual crash reasons:

Cannot find module '...': dependencies aren't installed. Run
Code:
npm ci
(or
Code:
npm install
) in the app folder as the site user.
EADDRINUSE: the port is already taken, often by an old copy of the app.
Code:
pm2 delete all
(as the site user), then start it once.
Missing environment variables or
Code:
.env
file: copy them over from your old server or your project's example file.
Wrong Node version: check
Code:
node -v
. Choose the Node.js version your app needs in the site's settings.
Build not run: Next.js, Nuxt and similar apps need
Code:
npm run build
before
Code:
npm start
.

After fixing, restart:

Code:

pm2 restart all

Step 4: App gone after a reboot
PM2 doesn't remember your apps across reboots unless you tell it to. As the site user, after the app runs correctly:

Code:

pm2 save
pm2 startup

Code:

pm2 startup

prints a command that starts with

Code:

sudo env PATH=...

. Copy that exact line and run it as root. Then reboot once to test.

Step 5: App dies under load or every few hours
Often the server runs out of memory and Linux kills the biggest process. Check:

Code:

free -h
dmesg -T | grep -i 'killed process' | tail

If you see your app there, add swap or more RAM, or limit the app's memory so PM2 restarts it cleanly before the system kills it:

Code:

pm2 start npm --name myapp --max-memory-restart 400M -- start

Also check Fix 502 Bad Gateway in CloudPanel for general 502 causes.

Quick checklist

Code:
pm2 list
(as the site user) shows the app online.
Code:
ss -tlnp | grep node
shows it on the App Port, on 127.0.0.1 or 0.0.0.0.
Code:
curl -I http://127.0.0.1:3000
on the server returns a response.
Code:
pm2 save
and the startup command are done.

If all four are true, the site works.

Sources: PM2: quick start · PM2: startup script · CloudPanel: site:add:nodejs

More CloudPanel troubleshooting

Applies to CloudPanel v2 on Ubuntu and Debian, October 2026. Replace 3000 with your site's App Port.

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