ruvnet/ruflo · error

[router] arch router failed with transient error, attempting

Error message

[router] arch router failed with transient error, attempting fallback

What it means

Log warning in makeRouterEndpoint: the arch router failed with a transient error (5xx, timeout, network) rather than a policy error (401/402/403); routing continues with the fallback model chain instead of hard-failing.

Source

Thrown at ruflo/src/ruvocal/src/lib/server/router/endpoint.ts:276

		const routeSelection = await archSelectRoute(sanitizedMessages, undefined, params.locals);

		// If arch router failed with an error, only hard-fail for policy errors (402/401/403)
		// For transient errors (5xx, timeouts, network), allow fallback to continue
		if (routeSelection.routeName === ROUTER_FAILURE && routeSelection.error) {
			const { message, statusCode } = routeSelection.error;

			if (isPolicyError(statusCode)) {
				// Policy errors should be surfaced to the user immediately (e.g., subscription required)
				logger.error(
					{ err: message, ...(statusCode && { status: statusCode }) },
					"[router] arch router failed with policy error, propagating to client"
				);
				throw statusCode ? new HTTPError(message, statusCode) : new Error(message);
			}

			// Transient errors: log and continue to fallback
			logger.warn(
				{ err: message, ...(statusCode && { status: statusCode }) },
				"[router] arch router failed with transient error, attempting fallback"
			);
		}

		const fallbackModel = config.LLM_ROUTER_FALLBACK_MODEL || routerModel.id;
		const { candidates } = resolveRouteModels(routeSelection.routeName, routes, fallbackModel);

		let lastErr: unknown = undefined;
		for (const candidate of candidates) {
			try {
				logger.info(
					{ route: routeSelection.routeName, model: candidate },
					"[router] trying candidate"
				);
				const ep = await createCandidateEndpoint(candidate);
				const gen = await ep({ ...params });
				return metadataThenStream(gen, candidate, routeSelection.routeName);

View on GitHub (pinned to fa13ee4ad6)

Solutions

1. Verify the primary Arch router endpoint is reachable and LLM_ROUTER_ARCH_BASE_URL is correct; the fallback path is expected behavior for transient failures, so repeated occurrences indicate a network or service health problem to fix at the router.

When it happens

Trigger: Thrown at ruflo/src/ruvocal/src/lib/server/router/endpoint.ts:276 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of ruvnet/ruflo@fa13ee4ad6 (2026-08-18). Data as JSON: /api/errors/2b965db69da9399d. Report an issue: GitHub.