Wei Li It's worh a try but I don't think it's fixed in the latest version. I think we should either handle the events that Gerard Ryan mentioned explicitely (logout and update_password) and/or add a null check to this method: https://github.com/aerogear/keycloak-metrics-spi/blob/master/src/main/java/org/jboss/aerogear/keycloak/metrics/PrometheusExporter.java#L102