mcp-mcp-endpoint-encodin-when-using-mcp-inspector-sse-based-client-the-clie-a50884cc

THEN Ensure your MCP server's POST message endpoint is at the path `<SSE_endpoint>/messages`. If using a custom router, either adjust the route or migrate to the streamable HTTP transport as SSE is deprecated. Verify documentation for any implicit endpoint transformations.

// In an Express server with SSE at /sse and POST messages expected at /messages:
app.post('/messages', (req, res) => { /* handle messages */ });
// But Inspector will POST to /sse/messages, so either change server route to '/sse/messages' or use the correct URL from the SSE event.