localhost doesn't work on WSL2

[mvjl000]

I'm using zsh WSL Ubuntu on windows 10, and when I try to run something on localhost (currently Node Express app) my browser can't find anything on http://localhost:8080 (port is correct). This same situation is in Create React App. No answer from http://localhost:3000, but 'On Your Network' http://...:3000 it works. However, when i switch to powershell, everything is as it should be.

Environment

Windows 10
Ubuntu 20.04
WSL2

Steps to reproduce

npm start

Expected behavior

Response on http://localhost:8080

Actual behavior

No response on http://localhost:8080, but it says:

Error: listen EADDRINUSE: address already in use :::8080

[jung-youjin]

Hi! I've faced similar issue previously and turned out that port 8080 was already in use by other node. You can try lsof -i :8080 or lsof -c node to view the list and kill whichever process that is in duplicate by kill -9 "PID". Hope this helped!

[therealkenc]

'On Your Network' http://...:3000 it works

There is no repro here, but if ... is your WSL2 ip address and it works, this is almost certainly a variation of #4851 (and/or #5298). The EADDINUSE on ipv6 will be because it is in use, especially if you are bouncing between Windows node and WSL node.

Use can use following to debug what is actually listening

$ netstat -nlt
$ netstat.exe -a -n -p TCP