Authentication requires a port 3456 that's unavailable because it's running another process

Shopify Discussion
1

I am trying learn shopify development and creating a first app. Upon doing the initial npm run dev, I am thrown an error stating “Authentication requires a port 3456 that’s unavailable because it’s running another process. Terminate that process?”

If I choose to kill the process, it again throws the error stating “missing argument”.

Unknown error                                                                                           │
│                                                                                                          │
│  To investigate the issue, examine this stack trace:                                                     │
│    at handler (@shopify/cli-kit/src/public/node/error.ts:127)                                            │
│      fatal = new BugError(maybeError?.message ?? 'Unknown error')                                        │
│    at (@shopify/cli-kit/src/public/node/error-handler.ts:37)                                             │
│      return handler(error)

I checked several times to see which app/process is blocking the port but nothing comes up.

I am using openSUSE Linux for the development.

Any pointers would be greatly appreciated.

2

Your computer might have another node app running on port 3456. You can use the following command to kill it and then npm run dev again.

sudo killall node
3

yeah, I tried doing that but it didn’t work. After a lot of tinkering I ran the command with sudo and surprisingly it started to work; didn’t get any notification for port blocked, etc.

I have no clue why does it need elevated privileges.

sudo npm run dev
4

Confirming this is still an issue (in openSuse tumbleweed) and fix still works

5

I’m having the same issue, on openSUSE Linux, Shopify CLI 3.61.2

6

Instead of running “shopify app dev” prefix it with HOST eg.

HOST=127.0.0.1 shopify app dev

Why?

Because Shopify CLI uses https://www.npmjs.com/package/get-port-please, which by default checks port on HOST env variable. On my OpenSuse HOST env var is set to “linux…”, and checking any port on “linux…” HOST fails.