DTK0051: Connection Meta Serve Failed
Message
Failed to serve the RPC connection meta at "
{base}".
Cause
Each devframe mounted into Vite DevTools (Terminals, Messages, the Devframe Inspector, and any createPluginFromDevframe integration) is served as a same-origin iframe at its own base path, e.g. /__devframes-plugin-terminals/. Its SPA discovers the RPC/WebSocket endpoint by fetching ./__connection.json relative to that base, so the host serves the connection meta at each mounted base via mountConnectionMeta.
This diagnostic is reported when that request-time handler cannot resolve the connection meta — for example if the RPC/WS server failed to initialize, so the getter the host was handed rejects. When it happens, the SPA responds with a 500 and cannot connect: its panel stays empty (Terminals) or stuck loading (Inspector).
Example
The WebSocket server throws during startup, so the deferred connection-meta getter passed to the host rejects when the Terminals iframe requests /__devframes-plugin-terminals/__connection.json.
Fix
The devframe SPA mounted at this base cannot discover the RPC endpoint. Check the dev server logs for the underlying cause (surfaced as the diagnostic's cause), resolve it, and reload the page.
Source
packages/kit/src/node/vite-host.ts— themountConnectionMetamiddleware reports this when resolving the connection meta throws.