grpc/grpc-go · error

xds_wrr_locality: config generated %v is invalid: %v

Error message

xds_wrr_locality: config generated %v is invalid: %v

What it means

Returned by wrr_locality UpdateClientConnState (internal/xds/balancer/wrrlocality/balancer.go:182) when the weighted-target config it generated from the endpoints/weights fails to parse via the child parser. This is an internal invariant violation — the generated config should always be valid — so it generally indicates a bug or an endpoint with an invalid locality string.

Source

Thrown at internal/xds/balancer/wrrlocality/balancer.go:182

		// shouldn't happen though (this attribute that is set actually gets
		// used to build localities in the first place), and thus don't error
		// out, and just build a weighted target with undefined behavior.
		locality := xdsinternal.LocalityString(xdsinternal.LocalityIDFromEndpoint(ep))
		ai, ok := getAddrInfo(ep)
		if !ok {
			return fmt.Errorf("xds_wrr_locality: missing locality weight information in endpoint %q", ep)
		}
		weightedTargets[locality] = weightedtarget.Target{Weight: ai.LocalityWeight, ChildPolicy: lbCfg.ChildPolicy}
	}
	wtCfg := &weightedtarget.LBConfig{Targets: weightedTargets}
	wtCfgJSON, err := json.Marshal(wtCfg)
	if err != nil {
		// Shouldn't happen.
		return fmt.Errorf("xds_wrr_locality: error marshalling prepared config: %v", wtCfg)
	}
	var sc serviceconfig.LoadBalancingConfig
	if sc, err = b.childParser.ParseConfig(wtCfgJSON); err != nil {
		return fmt.Errorf("xds_wrr_locality: config generated %v is invalid: %v", wtCfgJSON, err)
	}

	return b.child.UpdateClientConnState(balancer.ClientConnState{
		ResolverState:  s.ResolverState,
		BalancerConfig: sc,
	})
}

func (b *wrrLocalityBalancer) ResolverError(err error) {
	b.child.ResolverError(err)
}

func (b *wrrLocalityBalancer) UpdateSubConnState(sc balancer.SubConn, state balancer.SubConnState) {
	b.logger.Errorf("UpdateSubConnState(%v, %+v) called unexpectedly", sc, state)
}

func (b *wrrLocalityBalancer) Close() {
	b.child.Close()

View on GitHub (pinned to 03255a9237)

Solutions

1. Inspect the underlying error (%v) to see which target/weight the child parser rejected
2. Verify endpoint locality weights are sane non-zero values
3. Report it upstream if it reproduces with a valid xDS resolver state

if err := bal.UpdateClientConnState(state); err != nil {
    if strings.Contains(err.Error(), "config generated") {
        logger.Errorf("internal wrr_locality invariant violated; report upstream: %v", err)
    }
    return err
}

When it happens

Trigger: UpdateClientConnState builds weightedTargets from endpoints, marshals it to JSON, and the weighted_target parser rejects it. Only reachable if a generated weight/target combination is invalid.

Common situations: A zero or overflowing locality weight; an internal version mismatch between wrrlocality and weightedtarget; effectively never seen in production — treat as a bug report candidate.

Related errors

• xds_wrr_locality: invalid LBConfig: %s, error: %v
• xds_wrr_locality: missing locality weight information in end
• ringhash: expected xDS config selector to set the request ha
• OutlierDetectionLoadBalancingConfig.interval = %s; must be >
• OutlierDetectionLoadBalancingConfig.base_ejection_time = %s;

AI-assisted analysis of grpc/grpc-go@03255a9237 (2026-08-07). Data as JSON: /api/errors/50525c786926ac6f. Report an issue: GitHub.