microsoft / microsoft/vscode-js-debug

Node 24.20+ concurrent localhost endpoint probes cause attach failures

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#2,416 1 comment 0 reactions 1 assignee View on GitHub

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Since Sep 18, 2026.

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Description

  1. Open an empty folder and create .vscode/launch.json:

    {
  "version": "0.2.0",
  "configurations": [
    {
      "name": "Attach over localhost",
      "type": "node",
      "request": "attach",
      "address": "localhost",
      "port": 9229,
      "timeout": 30000,
      "trace": true
    }
  ]
}

  2. In terminal, start an inspector that listens only on IPv4:

    node --inspect-brk=127.0.0.1:9229 -e 'setInterval(() => {}, 1 << 30)'

  3. Run Attach over localhost in latest vscode insiders. The attach fails.

  4. Change address to 127.0.0.1 and run it again. The attach succeeds.

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