Work through these in order:- Firstly Confirm the exact URL. For a shared connector it must be exactly https://connect.composio.dev/mcp ,no trailing slash, no /sse, no bare domain. Composio Connect is an MCP server at https://connect.composio.dev/mcp. Old rube.app/mcp or mcp.composio.dev/... links you may have copied from a blog are a different surface and will throw exactly this error.

Secondly If you pasted a session MCP URL, that's the bug. Session endpoints are read off session.mcp as a URL and headers, and both are meant to be passed to your framework's MCP client. Composio custom connector UI can't send those headers, it takes a URL plus optionally an OAuth Client ID/Secret under Advanced settings, nothing else. Unauthenticated, that endpoint won't resolve → "no MCP server found / no access." Use connect.composio.dev/mcp

And last but not the least 3. "Does not have access to it" is literal. If the URL was generated under a different Composio org/project than the account you just logged in with, or the session was deleted/regenerated, it 404s for you. Check in the dashboard which project owns it.

Clear the stale entry. On the reference ID: ofid_9593e35f7ed86e75 is an Anthropic-side identifier, not a Composio one,.Composio support can't look it up. If steps 1–4 don't fix it, file it at github.com/anthropics/claude-ai-mcp (they track exactly these), and separately ping support@composio.dev or the Composio Discord.