[BUG] OAuth login fails with “Missing redirect_uri parameter” — Max

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Claude Code OAuth login fails with "Invalid OAuth request — Missing redirect_uri parameter" after completing the full email verification flow. Max subscription is active and confirmed at claude.ai/settings. Cannot authenticate at all — completely blocked from using Claude Code.

The exact flow:

1. Run claude in terminal
2. Press c to copy the OAuth URL
3. Paste URL in Chrome (already logged into claude.ai with active Max subscription)
4. Enter email address and click send
5. Screen changes to ask for verification code
6. Receive email from Anthropic with a link
7. Click the link in the same browser — it generates a verification code
8. Copy the code, go back to the original tab, paste the code
9. Click submit
10. ERROR: "Invalid OAuth request — Missing redirect_uri parameter"

Additional errors observed:

• When browser is NOT logged into claude.ai: "You need Claude Max or Pro to connect to Claude Code" — even though Max is active
• Intermittently: "An error occurred while sending your login link"

Previously working fine. Broke after session expired, possibly related to April 7-8 authentication incidents on status.claude.com.

Tested on 2 devices (MacBook Air + Ubuntu 24.04 VPS), 3 browsers + incognito, cleared cache/cookies, deleted ~/.claude and ~/.config/claude-code, reinstalled Claude Code, no ANTHROPIC_API_KEY set. Cannot run /doctor or /bug because they require authentication.

Related issues: #19280, #44252, #44257, #44719, #1484

What Should Happen?

After submitting the correct verification code, Claude Code should complete OAuth authentication and start a session using my Max subscription.

Error Messages/Logs

Error 1: "Solicitação OAuth inválida — Parâmetro redirect_uri ausente" ("Invalid OAuth request — Missing redirect_uri parameter")

Error 2: "É necessário ter Claude Max ou Pro para conectar ao Claude Code" ("You need Claude Max or Pro to connect to Claude Code")

Error 3: "Ocorreu um erro ao enviar seu link de login" ("An error occurred while sending your login link")

Environment:
- Claude Code version: Latest (fresh install April 11, 2026)
- Node.js: v24.14.1
- OS: macOS (MacBook Air) + Ubuntu 24.04 (VPS)
- Account: Claude Max (active)
- Auth method: Email (corporate Microsoft 365 Business)
- ANTHROPIC_API_KEY: not set (confirmed empty)

Steps to Reproduce

1. Run claude in terminal on macOS
2. Press c to copy the OAuth URL
3. Open Chrome (already logged into claude.ai with active Max subscription)
4. Paste the OAuth URL in the browser
5. Enter email address (corporate Microsoft 365 Business) and click send
6. Screen changes to ask for a verification code
7. Receive email from Anthropic with a verification link
8. Click the link in the same browser — it opens and generates a verification code
9. Copy the code
10. Go back to the original tab and paste the code
11. Click submit
12. ERROR: "Invalid OAuth request — Missing redirect_uri parameter"

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

Unknown — was working before April 7-8, 2026 authentication incidents

Claude Code Version

Latest (fresh install via npm, April 11, 2026)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

• Also tested on Ubuntu 24.04 VPS via SSH — same error
• Tested on 3 different browsers + incognito mode — same error
• No ANTHROPIC_API_KEY set (confirmed empty)
• Max subscription confirmed active at claude.ai/settings
• Deleted ~/.claude and ~/.config/claude-code, reinstalled — same error
• Cannot run /doctor or /bug because they require authentication first
• This appears to be a server-side OAuth configuration issue, not client-side
• Related issues: #19280, #44252, #44257, #44719, #1484