pm2 start app returning 502

--- PM2 report ----------------------------------------------------------------
Date : Thu Jul 25 2024 16:06:56 GMT+0000 (Coordinated Universal Time)

--- Daemon -------------------------------------------------
pm2d version : 5.4.2
node version : 18.19.1
node path : not found
argv : /usr/bin/node,/usr/local/lib/node_modules/pm2/lib/Daemon.js
argv0 : node
user : root
uid : 0
gid : 0
uptime : 0min

--- CLI ----------------------------------------------------
local pm2 : 5.4.2
node version : 18.19.1
node path : not found
argv : /usr/bin/node,/usr/local/bin/pm2,report
argv0 : node
user : root
uid : 0
gid : 0

--- System info --------------------------------------------
arch : x64
platform : linux
type : Linux
cpus : Intel(R) Xeon(R) CPU E5-2686 v4 @ 2.30GHz
cpus nb : 1
freemem : 502251520
totalmem : 1003954176
home : /root

--- PM2 list -----------------------------------------------
┌────┬────────────────────┬──────────┬──────┬───────────┬──────────┬──────────┐
│ id │ name │ mode │ ↺ │ status │ cpu │ memory │
└────┴────────────────────┴──────────┴──────┴───────────┴──────────┴──────────┘

--- Daemon logs --------------------------------------------
/root/.pm2/pm2.log last 20 lines:
PM2 | 2024-07-25T16:06:56: PM2 log: ===============================================================================
PM2 | 2024-07-25T16:06:56: PM2 log: --- New PM2 Daemon started ----------------------------------------------------
PM2 | 2024-07-25T16:06:56: PM2 log: Time : Thu Jul 25 2024 16:06:56 GMT+0000 (Coordinated Universal Time)
PM2 | 2024-07-25T16:06:56: PM2 log: PM2 version : 5.4.2
PM2 | 2024-07-25T16:06:56: PM2 log: Node.js version : 18.19.1
PM2 | 2024-07-25T16:06:56: PM2 log: Current arch : x64
PM2 | 2024-07-25T16:06:56: PM2 log: PM2 home : /root/.pm2
PM2 | 2024-07-25T16:06:56: PM2 log: PM2 PID file : /root/.pm2/pm2.pid
PM2 | 2024-07-25T16:06:56: PM2 log: RPC socket file : /root/.pm2/rpc.sock
PM2 | 2024-07-25T16:06:56: PM2 log: BUS socket file : /root/.pm2/pub.sock
PM2 | 2024-07-25T16:06:56: PM2 log: Application log path : /root/.pm2/logs
PM2 | 2024-07-25T16:06:56: PM2 log: Worker Interval : 30000
PM2 | 2024-07-25T16:06:56: PM2 log: Process dump file : /root/.pm2/dump.pm2
PM2 | 2024-07-25T16:06:56: PM2 log: Concurrent actions : 2
PM2 | 2024-07-25T16:06:56: PM2 log: SIGTERM timeout : 1600
PM2 | 2024-07-25T16:06:56: PM2 log: ===============================================================================

Start by reproducing the pm2 start app command and investigating the reported 502 alongside the supplied PM2 5.4.2 report. The issue names no source file, test, application configuration, or proxy setup, so completion would require an agreed reproduction and a verified fix or documented cause.