[BUG]

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?

I'm unable to log into claude.ai on any new device or browser with my existing individual Pro account. This is not a Claude Code CLI-specific bug, but per the precedent set in #36797, #39788, #51002, #57164, and #60022, I'm filing it here because it's a backend authentication/identity-mapping issue that Fin AI Support (Anthropic's support bot) confirmed it cannot investigate or resolve for individual Pro accounts.

What Should Happen?

Clicking the magic link received via email should authenticate me into my existing Pro account on the browser/device where I requested it. Instead, I'm redirected back to the sign-in screen with no error message, and no path back into my account.

Error Messages/Logs

Two distinct symptoms observed on different days:

1. Initially: "There was an error sending you a login link. If the problem persists contact support for assistance." (shown immediately upon requesting the link)

2. After that resolved on its own: clicking "Sign in" in the received email returns to the claude.ai sign-in page (email entry screen) with no error message displayed at all.

Steps to Reproduce

1. Go to claude.ai on any browser/device other than my already-authenticated session
2. Click "Continue with email"
3. Enter my existing Pro account email address
4. Receive the "Your secure link to Claude.ai is here" email
5. Click "Sign in" in the email

Tested and ruled out as causes:

• Same browser/tab/session used to request it, clicked within 10 minutes
• Direct URL paste instead of clicking the button
• Different browser (Safari vs. Chrome)
• Different device (Mac vs. iPhone)
• Different network (home Wi-Fi, alternate Wi-Fi, cellular data)
• iCloud Private Relay on and off
• Default Safari profile only (no separate profiles in use)

Every combination results in being returned to the sign-in page — never authenticated.

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

N/A — not a version-specific regression. This is web-based magic-link authentication; my last successful login (on my currently-active device) predates this issue.

Claude Code Version

2.1.223 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

• Support conversation with Fin AI Agent (full troubleshooting history documented): Conversation ID 215475374591625
• Related prior reports of the same backend auth-routing pattern: #36797, #39788, #51002, #57164, #60022
• Willing to verify account ownership via active session and/or payment method details privately if needed
• Screenshots available on request: "error sending login link" screen, sign-in email, redirect-back-to-login behavior