[SOLVED] "address already in use" error after forwarding ports between WSL2 and Windows

"address already in use" error after forwarding ports between WSL2 and Windows

Port-forwarding with netsh interface portproxy is somehow blocking the ports that processes on WSL2 need to use.

I ran a PowerShell script from this blog in order to do port-forwarding between WSL2 and Windows 11.

However, when I start some applications that are supposed to bind the ports, it shows "address already in use" errors.

Error from docker-compose service (MongoDB):

ERROR: for service_name_1  Cannot start service mongo: driver failed programming external connectivity on endpoint service_name_1: Error starting userland proxy: listen tcp4 0.0.0.0:27017: bind: address already in use

Error from FastAPI:

[Errno 98] Address already in use

Strange thing is that these errors occur when there are no WSL processes up on those ports. Running these commands in WSL give me nothing:

lsof -i :27017
sudo netstat -nlp | grep 27017

However, there is one Windows process (svchost) that is using the port:

PS > Get-NetTCPConnection -LocalPort 27017

LocalAddress                        LocalPort RemoteAddress                       RemotePort State       AppliedSetting OwningProces
                                                                                                                        s
------------                        --------- -------------                       ---------- -----       -------------- ------------
0.0.0.0                             27017     0.0.0.0                             0          Listen                     12732

PS > Get-Process -Id 12732

Handles  NPM(K)    PM(K)      WS(K)     CPU(s)     Id  SI ProcessName
-------  ------    -----      -----     ------     --  -- -----------
    401      45     2824      11268       0.05  12732   0 svchost

When I kill this process, the "address already in use" errors do not appear anymore, but port-forwarding doesn't work propertly still. They were working just fine until today, and I can't figure out what could have possibly gone wrong.

Thanks for your help!

Solution

I was running into this same problem from the latest WSL release!

What worked for me is upgrading to a preview version of WSL that fixes this issue. https://github.com/microsoft/WSL/releases/tag/1.2.1

After installing the preview msixbundle, worked for me :)