I currently have CentOS 7.6, Windows Server 2016, and Ubuntu 16.04 LTS catalogs.
These catalogs work very well.
However, there is a problem with the Ubuntu 18.04 LTS catalog.
This is distributed with both IPs in the network profile and IPs in the template.
I referred to
How to make guest customization work on Ubuntu18.04 Server and Desktop (56409)
Guest OS Customization will fail for Ubuntu 18.04 Server LiveCD (54986)
But, KB didn't help.
And I also configure "customization spec" in blueprint.
Please advice to me.
if you question is around the guest os customization of specified version of ubuntu only.
start troubleshooting with following steps.
Use the template directly in vCenter server and deploy a VM using same custom spec that you are planning to use from vRA, see if this manual deployment goes through. Take it from there