Bug: Magnific MCP OAuth flow fails — session state lost between authenticate and complete_authentication

Status Fixed / completed

Maintainer reply None cached

Activity 3 comments · opened Jun 20, 2026 · closed Jun 20, 2026

Description

When using the Magnific MCP server (https://mcp.magnific.com/) via HTTP transport in Claude Code desktop app, the OAuth flow consistently fails with:

"No OAuth flow is in progress for magnific. Call mcp__magnific__authenticate first, then retry with the callback URL."

This happens even though authenticate was just called successfully moments before.

Steps to Reproduce

Add the server: claude mcp add --transport http magnific https://mcp.magnific.com/
Call mcp__magnific__authenticate → receive auth URL
Open the URL in the browser, complete OAuth login
Copy the callback URL (http://localhost:<port>/callback?code=...&state=...) from the browser address bar
Call mcp__magnific__complete_authentication with the callback URL

Expected Behavior

Authentication completes successfully and Magnific tools become available.

Actual Behavior

complete_authentication returns: "No OAuth flow is in progress for magnific."

Root Cause (suspected)

The MCP connection drops and reconnects between step 2 and step 5 (visible in the session as repeated "MCP server disconnected / reconnected" events). On reconnection, the OAuth session state is reset, so complete_authentication finds no active flow.

Tried 3+ times — same result every time. The issue appears to be a race condition between the MCP server's session lifecycle and the OAuth flow duration (the user needs a few seconds to log in and copy the callback URL).

Environment

Claude Code v0.2.1
macOS 15 (Mac Mini M4 Pro)
Transport: HTTP (--transport http)
MCP server: https://mcp.magnific.com/

View original on GitHub ↗

3 Comments

github-actions[bot] · 3 months ago

Found 1 possible duplicate issue:

https://github.com/anthropics/claude-code/issues/67705

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

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Zarbel83 · 3 months ago

Closing this — turns out the issue was a misunderstanding on my end.

Magnific was already available as a claude.ai Magnific connector (authenticated via the claude.ai account, like Canva, Gmail, etc.). The claude mcp add --transport http magnific https://mcp.magnific.com/ command added a redundant second server that was trying to do OAuth independently and failing.

The OAuth failure is still technically real (the MCP session drops between authenticate and complete_authentication, resetting the state), but since the integration already works through claude.ai connectors, it's not a blocking issue for us. Leaving this here in case it's useful for others who don't have the claude.ai connector and try to set up Magnific manually via CLI.

github-actions[bot] · 1 month ago

This issue has been automatically locked since it was closed and has not had any activity for 7 days. If you're experiencing a similar issue, please file a new issue and reference this one if it's relevant.