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[FAQ Bot] NEW: Claude Code login fails in GitHub Codespaces with “localhost refused to #370

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alexeygrigorev merged 2 commits into from
Sep 9, 2026
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[FAQ Bot] NEW: Claude Code login fails in GitHub Codespaces with “localhost refused to #370

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NEW: Claude Code login fails in GitHub Codespaces with “localhost ref…
Sep 4, 2026
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Fix Codespaces login FAQ: How-question, Anthropic docs link (#370)
alexeygrigorev Sep 9, 2026
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23 changes: 23 additions & 0 deletions ...omcamp/misc/006_9a1eef9e91_claude-code-codespaces-localhost-refused-callback.md
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---
id: 9a1eef9e91
question: How do I fix Claude Code login failing with "localhost refused to connect"
in GitHub Codespaces?
sort_order: 6
---

Claude Code's OAuth login opens a browser tab pointing at `http://localhost:PORT/callback`. In GitHub Codespaces, that callback URL can fail to load because the browser reaches it through Codespaces' port-forwarding proxy instead of talking directly to the listener.

Workaround:
1. Run `claude` and let it open the login link in your browser.
2. When the page fails to load, copy the full callback URL from the address bar (for example `http://localhost:35251/oauth/callback?code=...`).
3. In a second terminal tab inside the same Codespace, run:

```bash
curl "http://localhost:35251/oauth/callback?code=..."
```

4. Your original `claude` terminal should log in immediately.

Why this works: the `curl` runs inside the Codespace on the same machine as the listener, so it bypasses the forwarding proxy.

If this still doesn't resolve it, check Anthropic's [Troubleshoot installation and login](https://code.claude.com/docs/en/troubleshoot-install) docs for other known causes.
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