Services getting same external IP address and SyncLoadBalancerFailed error

[cjendeberg]

What happened:

No traffic directed to service

What you expected to happen:

Log messages in ContainerLogV2 indicating service being called

How to reproduce it (as minimally and precisely as possible):

Don't know

Environment:

• Kubernetes version (use kubectl version): v1.34.6
• Cloud provider or hardware configuration: Azure
• OS (e.g: cat /etc/os-release): Ubuntu 22.04.5 LTS
• Kernel (e.g. uname -a): 5.15.0-1110-azure
• Install tools:
• Network plugin and version (if this is a network-related bug): azure overlay
• Others:

Anything else we need to know?:

Neither service manifest specified a static IP -- allocation was automatic

10 services alltogether in the same cluster had the same issue, i.e. 5 external IPs had 2 associated services each

The first service "imperium" created first (12:39), the second "vsbs" created ~80 min later (13:59), both ended up with 172.29.144.133. imperium was the service that was failing

Node information:
$kubectl get nodes -o wide | Select-Object -First 3
NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
aks-d4dsv5-12670993-vmss000000 Ready 4d23h v1.34.6 172.29.144.101 Ubuntu 22.04.5 LTS 5.15.0-1110-azure containerd://1.7.31-1
aks-d4dsv5-12670993-vmss000001 Ready 4d23h v1.34.6 172.29.144.100 Ubuntu 22.04.5 LTS 5.15.0-1110-azure containerd://1.7.31-1

Error message:

• SyncLoadBalancerFailed message
  kind: Event
  apiVersion: v1
  metadata:
  name: imperium-ep-liveevents-perpetuum-historical-service.18af923d9c2df04e
  namespace: imperium
  uid: 26f07593-f6c0-418d-aa80-4050999bba8d
  resourceVersion: '3776343'
  creationTimestamp: '2026-05-14T23:26:11Z'
  managedFields:

  • manager: cloud-controller-manager
    operation: Update
    apiVersion: v1
    time: '2026-05-16T08:24:49Z'
    fieldsType: FieldsV1
    fieldsV1:
    f:count: {}
    f:firstTimestamp: {}
    f:involvedObject: {}
    f:lastTimestamp: {}
    f:message: {}
    f:reason: {}
    f:reportingComponent: {}
    f:source:
    f:component: {}
    f:type: {}
    involvedObject:
    kind: Service
    namespace: imperium
    name: imperium-ep-liveevents-perpetuum-historical-service
    uid: dd354ded-78b5-44b4-9f31-ba2ae065dff2
    apiVersion: v1
    resourceVersion: '845698'
    reason: SyncLoadBalancerFailed
    message: >
    Error syncing load balancer: failed to ensure load balancer: PUT
    http://localhost:7788/subscriptions/4ff20024-87c5-48d1-bffc-16e0d83dce81/resourceGroups/mc_aks-qa-fordon-weu-rg_aks-qa-fordon-weu_westeurope/providers/Microsoft.Network/loadBalancers/kubernetes-internal

  ---

  RESPONSE 400: 400 Bad Request

  ERROR CODE: PrivateIPAddressIsAllocated

  ---

  {
  "error": {
  "code": "PrivateIPAddressIsAllocated",
  "message": "IP configuration /subscriptions/4ff20024-87c5-48d1-bffc-16e0d83dce81/resourceGroups/mc_aks-qa-fordon-weu-rg_aks-qa-fordon-weu_westeurope/providers/Microsoft.Network/loadBalancers/kubernetes-internal/frontendIPConfigurations/add354ded78b544b49f31ba2ae065dff is using the private IP address 172.29.144.133 which is already allocated to resource /subscriptions/4ff20024-87c5-48d1-bffc-16e0d83dce81/resourceGroups/mc_aks-qa-fordon-weu-rg_aks-qa-fordon-weu_westeurope/providers/Microsoft.Network/loadBalancers/kubernetes-internal/frontendIPConfigurations/a584f628508b2424ab7136e5a3ee99e7.",
  "details": []
  }
  }

  ---

source:
component: service-controller
firstTimestamp: '2026-05-14T23:26:11Z'
lastTimestamp: '2026-05-16T08:24:49Z'
count: 400
type: Warning
eventTime: null
reportingComponent: service-controller
reportingInstance: ''