While running the vSphere 6.7 VMware Migration Assistant I received the following error: This vCenter Server has extensions registered that cannot be upgraded to or may not work with the new vCenter Server. In my case, the extensions were no longer being used.  So, I chose to just remove the offending extensions. 1.  Create a snapshot or backup of your vCenter server. 2.  Log into the Managed Object Browser (MOB). https://vcenterfqdn/mob 3. Select Content. 4. Select ExtensionManager. 5. Capture the VALUE of the Extension you wish to remove.  (ex.com.vmware.vcHms): 6. Select UnregisterExtension 7. Enter the Value of the extension you wish to remove.  Then, select Invoke Method.  Confirm that  you receive the Result of Void. 8. […]