Troubleshooting

• The URL is rejected or returns "Invalid Host header": confirm it starts with https://, uses your exact workspace hostname, and ends in /api/v1/mcp/transport (or /api/v1/mcp/openai/transport for ChatGPT). If it is still rejected, MCP may not be enabled for your workspace; ask your Stackless contact.
• Authorization does not finish: allow browser redirects and pop-ups, sign in to the same Stackless workspace used in the endpoint, and click Authorize on the consent page.
• "Invalid or expired MCP session": your session was revoked, for example because you signed out of Stackless or your roles changed. Reconnect the server in your client and authorize again.
• A tool is missing, or a call fails with missing_permissions: tool visibility and execution follow your Stackless roles. Ask your administrator whether your role has the required permission, then reconnect so your client refreshes its tool list.
• A call fails with confirmation_required: the action is guarded. Review it in your client and approve it explicitly.
• A call fails with call_in_progress or retry_cooldown: the same request is still running, or it was retried too quickly. Wait a few seconds and let the client check the result before retrying.
• A request stays queued: some operations, such as publishes and refreshes, are asynchronous. Let the agent or client check the returned operation until it succeeds, fails, or is cancelled. You can also follow the run in Operations.
• Terminal agent cannot connect: run uvx stackless-mcp==<version> doctor --base-url https://your-workspace.stacklessdata.com to check stored sign-in, connectivity, and capabilities, then run login again if the session expired.

For help, use Help > Report an Issue in Stackless or contact Stackless with your workspace hostname, the agent or client name, the time of the failure, and the non-secret error message. Never send an access token or session cookie.