Troubleshooting

Common issues when connecting to or using the Mixpost MCP server, and how to fix them.

Symptom	Likely cause and fix
401 / "Unauthenticated"	The personal key is missing, mistyped, expired or deleted. Check the Authorization: Bearer <personal-key> header, and create a new key, or rotate this one, if needed.
ChatGPT or Claude asks you to sign in again	The app was disconnected under Connected apps, or it went unused for more than 90 days. Connect it again and allow access.
The client offers no Sign in option	OAuth may be turned off (MIXPOST_OAUTH=false), or the instance is not reachable from the internet over HTTPS. Use a personal key instead, or make the instance publicly reachable.
Sign in fails with invalid_request	The client did not use PKCE with the S256 method, or its redirect URI does not match the one it registered. Update the client, or remove and add the connector again.
403 "This token cannot be used for this resource."	A token an AI client received with Sign in with OAuth was sent to the REST API. Those tokens only work on the MCP server — use a personal key, or an app client with REST API access.
The agent can't see a workspace	Its owner is not a member of that workspace. Add the user to the workspace, then ask the agent to list workspaces again.
"You do not have permission…" on create / update / delete	The token owner has the Viewer role. A Member or Admin role is required for write operations.
The client can't connect at all	The API may be turned off (MIXPOST_API_ACCESS_TOKENS=false), or the URL is wrong. Confirm the endpoint is the address you open Mixpost at followed by /mcp, path included if your instance has one — for example https://example.com/social/mcp.
The client won't add an HTTP server	Some clients only support local (stdio) servers — connect through the mcp-remote bridge shown in Connect your client.