Lync Server 2013 Forest Prep Issue - Task execution failed (Object reference not set to an instance of an object)
You will receive an preparation failed error regardles if you chose the wizard or the Enable-CsAdForest command.
It failes with:
Prepare Forest Active Directory setting exection failed on an unrecoverable error
Command execution failed: Value cannot be null.
Parameter name: InstanceToDelete
This is an wellknow issue in the installation process.
you must use the PowerShell command
Enable-CsAdForest -GroupDomain <AD Domain FQDN> -GroupDomainController <DC FQDN> -GobalCatalog <GC FQDN>
Author: Thomas Pött Managing Consultant Microsoft UC