Error "Internal Server Error" while changing VM placement policy in VMware Cloud director

Products

• VMware Cloud Director

Issue/Introduction

• "Internal Server Error" occurs while trying to change the Placement policy on VMs.
  
  
  
  
• In the debug information, you observe entries similar to below:
  
  Debug Information:
com.vmware.vcloud.api.presentation.service.InternalServerErrorException: Internal Server Error at com.vmware.vcloud.common.future.FutureUtil.convertExecutionException(FutureUtil.java:233)

com.vmware.vcloud.api.presentation.service.InternalServerErrorException: Internal Server Error
       ...
        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
        at java.base/java.lang.Thread.run(Thread.java:829)
Caused by: java.lang.NullPointerException
        at com.vmware.ssdc.backend.services.impl.RelocateVmActivity$SaveVmGroupInfoPhase.invoke(RelocateVmActivity.java:442)
        ... 7 more

Environment

VMware Cloud Director 10.5

VMware Cloud Director 10.6

Cause

This issue is caused by resource pool mismatches or absence between vCenter and VCD 

Resolution

1. Take snapshot/backup of VCD cells
2. Open an SSH session to any of the VCD cells
3. Fix the Resource pool mismatches as per command: ./cell-management-tool detect-rp-mismatches --fix-mismatch-with-vc
   Reference article: Detect Resource Pool mismatches