PrometheusErrorSendingAlertsToSomeAlertmanagers #

Meaning #

Prometheus has encountered more than 1% errors sending alerts to a specific Alertmanager.

Impact #

Some alerts may be lost.

Diagnosis #

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

Mitigation #

Set multiple AlertManager instances, spread them across nodes.