Dependency failure

Certificate expiration is a fully predictable failure mode, so renewal must be automated with independent expiry monitoring, and reconnect paths need circuit breakers so a recovering fleet of clients doesn't stampede shared APIs on its way back up.

Third-party provider risk runs much deeper than your direct dependencies — audit not just which services you integrate with but which cloud provider each one runs on, and verify that your deployment pipeline itself has no implicit dependencies on the same failing infrastructure you need to fix.

Autoscaling systems can hide defects that only trigger past capacity levels never previously exercised in production, so scaling logic must be tested well beyond historical peak, not just up to it.

A safety mechanism reacting to a bigger failure can amplify it. Watch for circular dependencies where the tools to fix an outage are taken out by it.

Your status page must be load-tested for outage-level traffic spikes, and incident communication must begin within five minutes of detection — not after internal triage is complete.

Redundancy plans must verify physical and network independence between supposedly separate failure domains, not just assume it from provider region boundaries.