HotAdd mode backup of virtual machine in VDDK fails with the error: Panic: Assert Failed: "_lockToken != __null"

Products

• VMware vSphere ESXi

Issue/Introduction

Symptoms:

• A HotAdd mode backup of a virtual machine fails with the error:
  
  Panic: Assert Failed: "_lockToken != __null"

Environment

Virtual Disk Development Kit 5.5
Virtual Disk Development Kit 5.0
Virtual Disk Development Kit 5.1
VMware Virtual Disk Development 1.2

Cause

This issue is triggered when a HotAdd backup fails to acquire a lock. As the lock is not acquired, the failure to check for NULL before releasing the lock results in an application stop. This issue can occur when an unusually large number of parallel HotAdd mode backups are running.

Resolution

This issue is resolved in VMware Virtual Disk Development Kit 5.5 Update 1, available at VMware Downloads.

For more information, see the VDDK 5.5.1 Release Notes.

To work around this issue when you do not want to upgrade, reduce the number of HotAdd mode parallel backups to reduce the lock contention.