tested with 4.6.0-0.nightly-2021-06-24-211140, followed the steps in comment 0, AlertmanagerReceiversNotConfigured alert was not fired again record: cluster:alertmanager_routing_enabled:max expr: clamp_max(sum(alertmanager_integrations), 1)
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory (OpenShift Container Platform 4.6.38 bug fix update), and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHBA-2021:2641