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Troubleshooting

Windows LocaltoNet HTTP tunnel address already in use on a port that worked yesterday

Posted by deborahm • July 22, 2026

This just started out of nowhere on Windows. The app itself still loads on localhost in the browser, but creating or restarting the tunnel now throws "address already in use" on the same port I was using yesterday, because apparently the gremlins needed a hobby too.

Before I start randomly killing processes, what are the usual things to check first here? Mostly wondering if LocaltoNet leaves old tunnels hanging around, if another tunneling app tends to grab the bind, or if there's a quick way to see what actually owns the port without turning this into an archeology project.

Comments (2)

deborahm Jul 22, 2026

Yeah, checking the actual owner of the port is the bit I needed, the annoying part is localhost still works so I wasn't sure if it was my app or LocaltoNet's listener that was colliding. I haven't checked with netstat yet, if it shows my own process already bound there does that usually mean LocaltoNet wants a different local bind port too, not just the app port?

savannahgray Jul 23, 2026

If netstat shows your app already bound there, I'd check whether LocaltoNet is trying to open that same local port itself instead of just forwarding to it, some tunnel tools have a separate "listen" port and a "target" port and the UI doesn't exactly make that obvious because apparently clarity is premium DLC. Also worth checking if you accidentally have a second tunnel profile pointing at the same port, I've had that happen and it looked way more mysterious than it was.

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