Issue:
PowerChute Network Shutdown v4.x fails to shutdown the vCenter Server VM or ESXi hosts when using a local account.

This issue manifests itself as follows when attempting to shut down ESXi hosts during a shut down sequence as seen in the PowerChute error log.

Product Line:
PowerChute Network Shutdown versions 4.x

Environment:
All support OS configured with VMware vCenter Server and ESXi host/s. 

Cause:
PowerChute attempts to log in with lower case user name

 e.g.
User created in ESXi host and entered in PowerChute as PCNSUSER
When PowerChute contacts the host it enters pcnsuser
The user is rejected since the ESXi host is expecting PCNSUSER (all upercase letters). 

Solution.
1 - Create user in the host/s with lower case letters. 
2 - To avoid having to use a lowercase username set the default sso domain to localos.
 Example: if using PCNSuser@localos set the default domain in vCenter to localos. This allows for connection to vCenter using the username "PCNSuser" without having to include "@localos" and use this in the PCNS UI. This would avoid PCNS converting the username to lowercase. 
The same would be true for vsphere.local accounts - whatever the default domain is set to you can just use the username without having to include the domain name, "@vsphere.local". 

See the attached videos for assistance with adding user to ESXi 6.7 host and vCenter Server 6.7