MCP connector errors
Preview
This feature is new and evolving. Details on this page may change as we
improve it.
When a connection attempt fails, Go verifies it on the spot and shows the
reason on the connector page and the connect card, together with the fix.
These messages can appear on any MCP connector.
| Go shows | What it means | How to fix it |
|---|---|---|
| The MCP server rejected the credentials. | The API key or OAuth client is wrong, expired, or revoked. | Press Re-enter credentials on the connector page or the connect card and paste fresh values. |
| The MCP server did not respond in time. | Temporary slowness or an outage at the provider. | Retry. Check the provider's status page if it persists. |
| The MCP server returned a server error. | The provider's MCP server is having problems. | Retry later. New credentials will not help. |
| The MCP server could not be reached. | The server URL is wrong or the provider's MCP endpoint is disabled. | Check the URL and the provider-side MCP setup. |
| The MCP server returned an error response. | The server answered but refused the request. | Finish setup in the provider's admin settings, then retry. |
| The MCP server returned a malformed response. | The URL does not point at an MCP endpoint. | Verify the server URL against the provider's documentation. |
| The MCP server URL is not allowed. | The URL is not a public https endpoint. | Update the server URL and retry. |
| The sign-in attempt expired or was invalid. | The authorization popup was abandoned or timed out. | Start the connection again. |
| The provider denied the sign-in request. | Sign-in was cancelled, or the organization requires admin approval. | If the provider mentioned admin consent (for example Microsoft AADSTS65001), ask a tenant admin to grant consent, then reconnect. |
| The provider refused to issue an access token. | The client ID or secret is wrong, or the callback URI is not registered. | Re-enter the credentials and confirm the callback URI matches exactly. |
| The provider refused to renew the access token. | Access was revoked on the provider's side. | Reconnect from the connector page. |
| The provider's sign-in service returned an invalid response. | A provider-side OAuth problem. | Retry. If it persists, check the provider's OAuth configuration. |
| The provider's sign-in endpoint is not allowed. | The OAuth token endpoint is not a public https URL. | This is a provider misconfiguration. Contact support. |
| The provider's sign-in service uses an unsupported authentication method. | This connector cannot be used with this provider yet. | Contact support. |
| The requested tool does not exist on the MCP server. | The server connected but does not expose this tool. | Refresh the tool list, or check the integration's scopes in the provider's admin settings. |
| The connection attempt failed. | Go could not classify the failure. | Retry from the connector page or the connect card. Re-enter credentials if it keeps failing. |
If the agent proposed the connector in chat, it sees the same error. You
can also ask it why the connector will not connect.
Updated about 1 hour ago
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