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ERR_SERVER_ALREADY_LISTEN

server already listen

What does this code mean?

Code ERR_SERVER_ALREADY_LISTEN · An issue reported by Node.js.

Official explanation · Original text

The server.listen() method was called while a net.Server was already listening. This applies to all instances of net.Server, including HTTP, HTTPS, and HTTP/2 Server instances.

Troubleshooting and diagnostic links

First check that the document's product, version, and environment match your situation.

Source and terms of use

Errors | Node.js v26.13.1 Documentation ↗

Creator: Node.js contributors; Joyent, Inc. and other Node contributors
License: MIT License (Node.js documentation)
Checked on: 2026-11-12

Modifications: English prose extracted; whitespace normalized; Korean context and classified official links added. Python code examples not redistributed.

Source details · Original licenses and notices