# An application in an Istio sidecar pod fails at startup because its first outbound calls happen before the Envoy sidecar is ready. Which setting fixes this?

Istio, Hard (Expert), Troubleshooting. https://k8wiz.com/uquiz/an-application-in-an-istio-sidecar-pod-fails-at-startup-because-its-first-outbound-calls-happen-before-the-envoy-sidecar-is-read

- A. A longer initialDelaySeconds on the app's readiness probe
- B. PILOT_ENABLE_PROTOCOL_SNIFFING=false on istiod
- C. restartPolicy: Never on the pod
- D. holdApplicationUntilProxyStarts: true

**Answer:** holdApplicationUntilProxyStarts: true

**Explanation:** The containers in a pod start together, so the app can send traffic while Envoy has no configuration yet, and those requests fail. holdApplicationUntilProxyStarts, set mesh-wide in meshConfig.defaultConfig or per pod with the proxy.istio.io/config annotation, starts the sidecar first and holds the app until Envoy is ready. On clusters with native sidecar containers, Istio can also run the proxy as a native sidecar, which avoids the race.