[BUG] OAuth redirect URI "not supported by client" on Mac Mini with Max subscription

[anwrks]

Preflight Checklist

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

What's Wrong?

Environment

• Claude Code version: 2.1.79
• Node: v25.6.1
• npm: 11.9.0
• OS: macOS (Mac Mini)
• Auth: Claude Max subscription (anwrks@gmail.com)

What's happening

OAuth login fails every time with "Authorization failed - Redirect URI http:/localhost:/callback is not supported by client."

The port changes each attempt (58582, 58725, 58776) but the error is the same.

Note: The redirect URI in the error shows a single slash (http:/localhost)
instead of double (http://localhost) — not sure if that's just the
error page display or the actual URI being sent.

Steps to reproduce

1. claude logout
2. claude
3. Select "Claude account with subscription"
4. Browser opens, logged in as correct account
5. Authorization failed page appears

Attempted fixes

• npm update -g @anthropic-ai/claude-code (updated successfully)
• claude logout + retry (multiple times)
• Different attempts produce different ports, same error

Expected

OAuth flow completes and Claude Code authenticates with Max subscription.

What Should Happen?

it should let me login.

Error Messages/Logs

Steps to Reproduce

Environment

• Claude Code version: 2.1.79
• Node: v25.6.1
• npm: 11.9.0
• OS: macOS (Mac Mini)
• Auth: Claude Max subscription (anwrks@gmail.com)

What's happening

OAuth login fails every time with "Authorization failed - Redirect URI http:/localhost:/callback is not supported by client."

The port changes each attempt (58582, 58725, 58776) but the error is the same.

Note: The redirect URI in the error shows a single slash (http:/localhost)
instead of double (http://localhost) — not sure if that's just the
error page display or the actual URI being sent.

Steps to reproduce

1. claude logout
2. claude
3. Select "Claude account with subscription"
4. Browser opens, logged in as correct account
5. Authorization failed page appears

Attempted fixes

• npm update -g @anthropic-ai/claude-code (updated successfully)
• claude logout + retry (multiple times)
• Different attempts produce different ports, same error

Expected

OAuth flow completes and Claude Code authenticates with Max subscription.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

No response

Claude Code Version

Environment - Claude Code version: 2.1.79 - Node: v25.6.1 - npm: 11.9.0 - OS: macOS (Mac Mini) - Auth: Claude Max subscription (anwrks@gmail.com) ## What's happening OAuth login fails every time with "Authorization failed - Redirect URI http:/localhost:/callback is not supported by client." The port changes each attempt (58582, 58725, 58776) but the error is the same. Note: The redirect URI in the error shows a single slash (http:/localhost) instead of double (http://localhost) — not sure if that's just the error page display or the actual URI being sent. ## Steps to reproduce 1. claude logout 2. claude 3. Select "Claude account with subscription" 4. Browser opens, logged in as correct account 5. Authorization failed page appears ## Attempted fixes - npm update -g @anthropic-ai/claude-code (updated successfully) - claude logout + retry (multiple times) - Different attempts produce different ports, same error ## Expected OAuth flow completes and Claude Code authenticates with Max subscription.

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

No response

[github-actions]

Found 3 possible duplicate issues:

1. OAuth authentication fails in headless/Docker environments: "Redirect URI not supported by client" #34917
2. [BUG] VS Code Extension OAuth broken on Linux - malformed redirect URI + subscription 401 #34662
3. [BUG] Claude in Chrome extension OAuth fails with "Redirect URI chrome-extension:// is not supported by client" - Cowork desktop app #34176

This issue will be automatically closed as a duplicate in 3 days.

• If your issue is a duplicate, please close it and 👍 the existing issue instead
• To prevent auto-closure, add a comment or 👎 this comment

🤖 Generated with Claude Code

[chk-mk]

I got the same issue on Windows with .79.

Workaround: You should be able to see the redirect URI embedded in the URI in your browser. Manually edit it to add the extra slash, then authorise again and it should work.

[christinalfy]

I also got the same issue on MacOS 15.7.4.

@chk-mk I tried your suggestion to copy http://localhost:56890/callback from the embedded URI
(Redirect URI http:/localhost:56890/callback is not supported by client.) but hit Authorization code not found

[christinalfy]

I also got the same issue on MacOS 15.7.4.

@chk-mk I tried your suggestion to copy http://localhost:56890/callback from the embedded URI (Redirect URI http:/localhost:56890/callback is not supported by client.) but hit Authorization code not found

oh works when it prompted me in terminal to choose Pro/Max account, thanks both!!

[chocobar]

Reproduction on Ubuntu 24.04 with Claude Code CLI

Environment: Ubuntu 24.04, GNOME desktop, Chromium browser, Claude Code (latest via npm)

Steps to reproduce

1. Install Claude Code: npm install -g @anthropic-ai/claude-code
2. Run: claude auth login
3. Select "Claude.ai account" (Pro/Max subscription)
4. Chromium opens the OAuth authorization URL

What happens

Claude Code constructs the correct redirect_uri with double slashes:

redirect_uri=http%3A%2F%2Flocalhost%3A32873%2Fcallback
→ http://localhost:32873/callback  ✓

This is visible in the initial login URL's returnTo parameter (double-encoded):

returnTo=%2Foauth%2Fauthorize%3F...%26redirect_uri%3Dhttp%253A%252F%252Flocalhost%253A32873%252Fcallback%26...

After completing login (entering email + magic code), the server redirects to the authorize page. During this server-side redirect, the redirect_uri is mangled — one slash is dropped:

redirect_uri=http:/localhost:32873/callback  ✗ (single slash)

The authorize endpoint then rejects this malformed URI: "Redirect URI http:/localhost:32873/callback is not supported by client."

Root cause

The bug is in the server-side handling of the returnTo redirect, not in Claude Code's URL construction. When the login page decodes the returnTo parameter and redirects to the authorize endpoint, it appears to normalize or double-decode the URL, collapsing // to / in the redirect_uri parameter value.

Workaround

A Chrome content script that detects redirect_uri=http:/localhost (single slash) on the authorize page and reloads with redirect_uri=http://localhost (double slash) before the error renders. This works because the underlying OAuth client registration does accept http://localhost:PORT/callback — it's only the server-side redirect that produces the malformed single-slash variant.

[someoneentirelyelse]

Thanks for the workaround tip, man.

Simpler workaround: before clicking Authorize on the auth page, fix the url manually. Find redirect_uri=http:/localhost and add the missing slash manually: redirect_uri=http://localhost. Click enter to reload the page, then click Authorize. You're in.

Can't believe Anthropic botched that one, though. Cost me a few hours to debug cringe