Unable to Assign License to vCenter – "Licenses could not be assigned" due to vAPI Endpoint Service Down

Products

• VCF Operations

Issue/Introduction

Users are unable to assign a license to vCenter and encounter the following error:

"Licenses could not be assigned to the selected vCenter systems."

MangementAdapter.log logs shows below error:

2026-03-24T08:33:32.086Z ERROR ManagementAdapter [ops@4413 threadId="" threadName="vcf-licensing" instanceId="58" ] [ (58) com. vmware. adapter.management. components. licensing. vcf. EntitlementMutationManager. assignEntitlementsToVc] - Login failed 
to VC <uuid> at <vCenter-FQDN>
com. vmware. vapi. client. exception. HttpProtocolException: HTTP response with status code 503 (enable debug logging for details): no healthy upstream 

Environment

VCF Operations 9.0

Cause

The issue occurs when the vAPI Endpoint service on the vCenter Server is stopped or not running.
This prevents communication required for license assignment, resulting in HTTP 503 errors.

Resolution

1. Take an SSH session to the vCenter Server.

2. Check the status of the vAPI Endpoint service:

service-control --status vapi-endpoint

3. If the service is stopped, start it using:

service-control --start vapi-endpoint

Once the service is running, retry the license assignment.

Additional Information

 

• HTTP 503 "no healthy upstream" typically indicates that the backend service required to process the request is unavailable.
• Ensuring all required vCenter services are running is critical for successful licensing operations.