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.