- Incorrect AlertManagerConfig causing Monitoring Operator Degradation, Facing the below issue:
UpdatingUserWorkloadAlertmanager: waiting for Alertmanager User Workload object changes failed: waiting for Alertmanager openshift-user-workload-monitoring/user-workload: context deadline exceeded: expected 1 replicas, got 0 updated replicas

- When running OCP 4.16.50, experiencing a persistent, high-impact issue where a single user-defined AlertmanagerConfig that references a non-existent Kubernetes Secret causes the Prometheus Operator to fail configuration generation, blocking the reconciliation of all other valid AlertmanagerConfigs in the user-workload monitoring stack (openshift-user-workload-monitoring).

    Openshift cluster version - 4.16.50 
   

This specific failure mode (**missing Secret**) persists even with the backported fix and in newer upstream Prometheus Operator versions (tested up to **0.85.0** upstream [here](https://gss--c.vf.force.com/apex/support#/cases/04323140/caseupdates/a0aHn00000a2B3ZIAU), linked to GitHub Issue **#7264** [here](https://gss--c.vf.force.com/apex/support#/cases/04323140/caseupdates/a0aHn00000a2AI4IAM)). The operator's Secret retrieval failure halts the entire configuration generation process, regardless of the URL validation fix.

Always

YAML to use:

apiVersion: monitoring.coreos.com/v1beta1
kind: AlertmanagerConfig
metadata:
  name: example
  namespace: noodles
spec:
  route:
    groupBy:
    - namespace
    receiver: msteams
  receivers:
  - name: msteams
    msteamsConfigs:
    - webhookUrl: 
        key: url # 
        name: my-workflow-webhook # k8s secret name in same namespace as AlertManagerConfig
      sendResolved: true
      title: "mytitle"
      text: "mytext" 

- Enable User Workload Monitoring
- Enable custom AlertManager configs
- Create a custom AlertManager config
- Check Prometheus Operator pod logs in User Workload Monitoring namespace to verify we see similar error
- Attempt to upgrade     

$ oc logs prometheus-operator-85fcd7664-xfstm | grep webhook | tail -n1
ts=2025-12-10T07:26:57.027512738Z level=error caller=/go/src/github.com/coreos/prometheus-operator/pkg/operator/resource_reconciler.go:557 msg="Unhandled Error" logger=UnhandledError err="sync \"openshift-user-workload-monitoring/user-workload\" failed: provision alertmanager configuration: failed to generate Alertmanager configuration: AlertmanagerConfig noodles/example: MSTeamsConfig[0]: unable to get secret \"my-workflow-webhook\": secrets \"my-workflow-webhook\" not found"

Then during upgrade:
$ oc get co
...
monitoring                                 4.19.19   False       True          True       2m      UpdatingUserWorkloadAlertmanager: waiting for Alertmanager User Workload object changes failed: waiting for Alertmanager openshift-user-workload-monitoring/user-workload: context deadline exceeded: expected 1 replicas, got 0 updated replicas
...

The monitoring operator should be in the available status and a non-existing secret should not impact on the AlertManagerConfig reconciliation.