unable to edit the template or migrate them

This error happend to me a day back. when moving the virtual templates to other host of a cluster.

Call "PropertyCollector.RetrieveContents" for object "propertyCollector" on vCenter Server "" failed

These setting keeps failing when trying to edit or convert these Virtual templates. After searching it in VMware knowledge base it seems to be an issue Virtual center which they will fix in future release.

Resolution

Go to the Virtual center console and select the ESX / ESXi host and select the VM or the Template.

1. Power off the virtual machine and note the ESX/ESXi host on which the virtual machine resides.
2. Right-click the virtual machine and click Remove from Inventory.
   
   Note: If the VM is removed from inventory using a vSphere client connected directly to the ESX host, it may still appear in the inventory view within vCenter Server as an orphaned VM. If this is the case, remove this orphaned VM from the vCenter Server inventory .
3. Browse the datastore and locate the virtual machine.
4. Right-click the .vmx file and click Add to Inventory.
5. If you are unable to add the virtual machine, close the vSphere Client from vCenter Server.
6. Log in directly to the ESX/ESXi host on which the virtual machine resides using the vSphere Client. To do this, you must know the root password.
7. Browse the datastore and locate the virtual machine.
8. Right-click the .vmx file and click Add to Inventory.
9. Log in to vCenter Server using the vSphere Client.

Note: You can also use this procedure for a template virtual machine. To do this, convert the template into a virtual machine, remove the virtual machine from inventory, re-register the virtual machine, and then convert it back to a template.

source : http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1025367