Invalid MCP state" after mobile disconnect/reconnect — persists across all devices and accounts

[wenggg945]

Environment

• Client: claude.ai (web) + Claude Desktop
• Notion accounts: 3 separate paid accounts
• Platforms tested: macOS, iOS, multiple browsers, incognito mode

What happened

1. Disconnected the Notion MCP connector from the claude.ai mobile interface
2. Attempted to reconnect from mobile — the OAuth flow behaved abnormally
3. From that point on, every reconnection attempt fails with:

Invalid MCP state. Please enable browser cookies and try again.

What I've tried

• Fully removing the connector and re-adding from scratch (multiple times)
• Multiple devices (desktop + mobile)
• Multiple browsers + incognito/private mode
• Three separate Notion accounts (all paid) — all fail with the same error
• Enabling third-party cookies for [*.]notion.so, [*.]notion.com, and [*.]claude.ai

Expected behavior
Removing and re-adding the connector should reset the OAuth state and allow a clean reconnection.

Actual behavior
The error persists regardless of device, browser, or Notion account used. This suggests the corrupted state is stored server-side (likely on the claude.ai backend), not on the client.

Hypothesis
The mobile disconnect/reconnect flow may have left a corrupted OAuth state parameter or session in the claude.ai backend. Standard connector removal does not appear to clear this. The Notion OAuth server (Cloudflare workers-oauth-provider) may also be involved in the state mismatch.

Impact
Notion MCP is completely unusable on this claude.ai account across all environments.

[luketritton]

Also getting this issue