Remote MCP server OAuth fails

Symptoms

• The authorization page fails to open or shows a redirect_uri error
• Tool calls return 401 some time after a successful login

Common causes

• The client version does not support OAuth or dynamic client registration (DCR) for remote MCP
• The redirect URI registered with the provider differs from the one the client uses
• The token expired and the client did not refresh it
• The requested scopes are insufficient

How to fix

1. Check that the client’s docs say it supports remote MCP authorization; if not, use the provider’s personal access token (PAT) option
2. Connect MCP Inspector to the same remote URL and run the flow on its own to tell server problems from client problems
3. Verify the redirect URI registered with the provider
4. Clear the server’s stored authorization in the client and sign in again
5. Request only the minimum scopes the task needs

Notes

• Treat tokens like passwords and keep them out of repositories