MCP troubleshooting

Choose the first failure you observe. Follow the checks in order and confirm the result before changing another setting.

What do you see? Choose a symptomServer does not appearENOENT / command not foundstdio: invalid JSON / connection closedHTTP 401: authorization requiredHTTP 403: access deniedHTTP 404: endpoint or sessionHTTP 405 in the browserConnected, but tool missing Show checks

This navigator provides instructions. It does not connect to your server or test your configuration. No logs or credentials are needed.

All symptoms at a glance

Server does not appearLoad configurationENOENT / command not foundStart the local processstdio: invalid JSON / connection closedCheck protocol outputHTTP 401: authorization requiredAuthorize the MCP endpointHTTP 403: access deniedPermissions and request contextHTTP 404: endpoint or sessionDistinguish path and sessionHTTP 405 in the browserInterpret the HTTP methodConnected, but tool missingInspect the tool list

Before you test again

Record the client, server version, transport, failing stage and expected result. Change one setting at a time. After connection succeeds, test the specific operation you need using a small, known resource.

• Client formats and configuration locations
• Check a prepared configuration
• Build a configuration from a registry entry