this is pobably related to TLS version support changes in vSphere 6.7. vSphere 6.7 supports only TLS 1.2 (but not 1.1 or 1.0 by default).
This KB article explains how to enable TLS 1.2 e.g. for PowerCLI (and other .NET Framework based programs): VMware Knowledge Base
I had a simular issue because I used another powershell module that used the older SSLv3 and TLS1. After commands form the non-powercli module where finished the whole powershell instance was reverted back to the default security mechanism. Then powercli will revert also back to the use of TLS which is not supported by default on Vcenter 6.7. Three possible solutions are:
- Easiest but not recommended: Revert vcenter back to use older TLS versions
- Run the commands for the other module in a seperate powershell instance, background job (start-job)
- After the other module commands are completed revert the session backup to TLS1.2
[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12