Error :"An error occurred during the initialization" when logging into the UI after upgrading to 10.6.1

Products

• VMware Cloud Director

Issue/Introduction

• After upgrading to VMware Cloud Director (VCD) version 10.6.1 the UI is not available and the below error is seen when trying to login:
  
   An error occurred during the initialization
• VCD is in multisite configuration.
• Only one site was upgraded to the VCD 10.6.1 version, the other site is still on VCD 10.5.x version.
• In /opt/vmware/vcloud-director/logs/vcloud-container-debug.log the following error is seen:
  
  DATE TIME | ERROR    | pool-jetty-41             | DefaultExceptionMapper         | Internal server exception | requestId=########-####-####-########5416,request=GET https://cloud.example.com/api/session,request Time=1738680580321,remoteAddress=##.##.##.##:56236,userAgent=vcd-client,accept=application/*+xml;version 39.0 java.lang.IllegalArgumentException: Unknown API version: 39.0.0-alpha

Environment

VMware Cloud Director 10.6.1

Cause

Multisite with site version 10.5.1 is using API Version 39.0.0-alpha, 10.6.1 no longer contains this version, renamed to 39.0.0

Resolution

Currently there is no resolution:

Workarounds:

OPTION 1
Revert Upgrade: Roll back to the previous working version of the software.

OPTION 2
Remove Multisite: Disconnect the multisite feature and revert to single sites. The multisite can be configured again once both sites have been upgraded to VCD 10.6.1. For additional information visit the documentation Configuring and Managing Multisite Deployments in Your VMware Cloud Director

OPTION 3 
Perform Upgrade: Ensure all sites within the Multisite Configuration are upgraded to version 10.6.1.