I need confirm about VCF version upgrade question. our customer has VCF3.9 environment. they want to upgrade the VCF 3.9 to VCF4.0, I thought it`s not supported, right? thanks any responses .
Not supported. See official docs:
If you use that approach you will break the inventory of managed entities in SDDC manager internal database.
The first step in the upgrading process is to upgrade the core components (Cloud Foundation Software). This is a key part of the upgrade process.
You should wait until there is a supported upgrade path.