It's ESX Version:7.0.3 with ISE Compatibility:ESXi 6.0. That's ISE check. For VM and upgrade its compatibility it require a shutdown that's the problem on production enviroment :).

I have upgraded from 3.1 to 3.2 in production enviroment with ESX 6.0 Compatibility.In logs "Required ESX Version 7.0 available to proceed with upgrade Only thing that it was increased was vCPU from 8 to 12. Guest OS:Red Hat Enterprise Linux 8 (64-bi...

This is working solution, thanks. You need to "Enable Certificate Authority" if it is disabled. Administration > System > Certificates > Certificate Authority > Internal CA Settings > Enable Certificate Authority