PrometheusErrorSendingAlertsToAnyAlertmanager #

Meaning #

Prometheus has encountered errors sending alerts to a any Alertmanager.

Impact #

All alerts may be lost.

Diagnosis #

Check connectivity issues between Prometheus and AlertManager cluster. Check NetworkPolicies, network saturation. Check if AlertManager is not overloaded or has not enough resources.

Mitigation #

Set multiple AlertManager instances, spread them across nodes.