VMware Aria Operations collector logs report 503 Service Unavailable for vCenter vmonapi

Products

• VCF Operations

Issue/Introduction

VMware Aria Operations (formerly vRealize Operations) fails to retrieve health data from a vCenter Server instance. The following error is observed in the /storage/logs/vcops/logs/collector.log on the Aria Operations node:

ERROR [pool-176865-thread-6] com.vmware.adapter3.vmwareinfrahealth.util.RestAPISession.getVmonApi - Failed: URL: https://<VCENTER_FQDN>/rest/appliance/vmon/service HTTP error code: 503 Service Unavailable

Environment

 

• VMware Aria Operations 8.18.x

• VMware vCenter Server 7.x / 8.x

 

Cause

The vmonapi (VMware Lifecycle Inventory) service is stopped or unresponsive on the target vCenter Server Appliance, preventing Aria Operations from executing REST API calls to the vmon endpoint.

Resolution

To resolve this issue, start the vmonapi service on the vCenter Server Appliance:

1. Open an SSH session (e.g., Putty) to the vCenter Server Appliance using root credentials.

2. Enable the Bash shell if prompted by typing shell.

3. Execute the following command to start the service: service-control --start vmonapi

4. Verify the service status to ensure it is running: service-control --status vmonapi

5. Monitor the Aria Operations collector.log to confirm that the 503 Service Unavailable errors have ceased.

Additional Information

Deprecation Notice: The APIs under /rest/appliance/vmon/service are scheduled for deprecation in future releases. For more details, refer to Broadcom KB 321044.