Ollama on Windows: Error: listen tcp 127.0.0.1:11434: bind: Only one usage of each socket address is normally permitted

Context

Source(s): https://github.com/ollama/ollama/issues/3575 Status: reported working by source, not reproduced by us.

Problem

Running ollama serve in a terminal on Windows fails immediately because port 11434 is already taken. The reporter lists rebooting, restarting the server, and killing the PID found with netstat as things already tried.

Error (redacted / normalized)

Error: listen tcp 127.0.0.1:11434: bind: Only one usage of each socket address (protocol/network address/port) is normally permitted.

Applies when

Ollama desktop install on Windows, running ollama serve manually in a terminal.

Confirm it is this problem

(our note) netstat -ano | findstr :11434 shows a LISTENING entry, and Task Manager shows ollama app / ollama running.

Not this when / boundary

A different 11434 error in the same thread, socket: The requested service provider could not be loaded or initialized, with nothing listening on the port - a different problem with no answer there. Also check the process name: if something other than Ollama holds the port, this fix does not apply.

Root cause

The Windows desktop install already runs Ollama in the background as two processes, ollama app and ollama. Killing only the server is not enough: ollama app starts it again on 11434 right away.

Variables

<port>: alternative port number you choose.

Fix

1. Quit the background copy: taskbar up-arrow (hidden icons) → right-click the Ollama icon → Quit. Or end both ollama app and ollama in Task Manager. → expect: (our note) netstat -ano | findstr :11434 prints nothing.
2. Run ollama serve again. → expect: starts without the bind error.
3. Only if you really need a server on another port: setx OLLAMA_HOST "127.0.0.1:<port>" /M, then restart Ollama. (Commenter suggestion, not confirmed.)

How to verify

ollama serve starts without the bind error.

What did not work

Rebooting, restarting the server, killing the PID from netstat (listed by the reporter as already tried). One commenter said a reboot was enough; (our note) a reboot alone often won't help because the app starts again at login.

Verified scope

Ollama for Windows, issue thread 2024-2026; checked Oct 2026