Fix Claude Code Login Auth Redirect Loop (2026)

The Error

Waiting for authentication...
Opening browser: https://console.anthropic.com/oauth/authorize?...
Error: Authentication callback not received. Timed out after 120 seconds.
Retrying... (attempt 3/3)
Error: Failed to authenticate. Please try again.

This error occurs when Claude Code's browser-based OAuth flow loops without completing. The browser opens, you authenticate, but the callback never reaches Claude Code.

TL;DR — Quick Fix

Clear the auth cache and re-login:

rm -rf ~/.claude/auth.json ~/.claude/.credentials && claude login

The Fix

Step 1: Clear the auth cache

rm -rf ~/.claude/auth.json
rm -rf ~/.claude/.credentials

Step 2: Kill any existing Claude Code processes

pkill -f "claude" 2>/dev/null

Step 3: Re-authenticate

claude login

If the browser does not open, manually copy the URL from the terminal and paste it in your browser.

Why This Happens

The OAuth flow starts a temporary local HTTP server to receive the callback. The loop occurs when:

• A firewall blocks localhost connections
• Another process occupies the callback port
• The browser redirects to an incorrect callback URL
• Stale auth tokens confuse the handshake
• Corporate SSO configurations interfere with the OAuth redirect chain

If That Does Not Work

Use API key authentication instead

export ANTHROPIC_API_KEY="sk-ant-api03-your-key"
claude "test"

Try a different callback port

claude login --port 9876

Check if localhost is resolving correctly

curl -s http://localhost:9876 2>&1
# Should show "connection refused" (port not in use), not a timeout

Disable VPN

Some VPNs intercept localhost traffic. Temporarily disable your VPN, run claude login, then re-enable it after authentication completes.

Prevention

Add this to your CLAUDE.md:

# Authentication
- Prefer API key auth (ANTHROPIC_API_KEY) over OAuth for CI/CD and headless.
- If OAuth loops, clear ~/.claude/auth.json and retry.
- Ensure no firewall rules block localhost on ports 9000-9999.

FAQ

Why does the OAuth login time out after 120 seconds?

Claude Code starts a local HTTP server and waits for the browser to redirect back after authentication. If the redirect cannot reach the local server (firewall, VPN, port conflict), the callback never arrives and Claude Code times out. Clear the auth cache with rm -rf ~/.claude/auth.json and ensure nothing is blocking localhost connections.

Can I skip browser-based login entirely?

Yes. Set the ANTHROPIC_API_KEY environment variable with your API key and Claude Code will use it directly without OAuth. This is the recommended approach for CI/CD pipelines, headless servers, and environments where browser access is restricted. Get your API key from console.anthropic.com.

Does corporate SSO cause the redirect loop?

Yes, corporate SSO and proxy configurations are a common cause. The SSO flow may add extra redirects that break the OAuth callback chain. Solutions: (1) use API key auth instead, (2) whitelist localhost:9000-9999 in your proxy configuration, or (3) temporarily bypass the corporate proxy for the authentication step.