I was about to execute couple of PowerCLI scripts and I encountered some strange issue while trying to connect to my vCenter server. I was using PowerCLI 6.5.1 which releases as a PowerShell module and I stopped using the old installed PowerCLI prompt.

There were no changes to the computer which I was using and suddenly it stopped the functionality and was throwing this error message when connecting to the vCenter using Connect-VIServer command. Here is the error message:

I searched the reason behind this and I was able to find that one of my colleague has installed the old version of PowerCLI command prompt in the same computer.

I uninstalled the older version, closed the PowerShell window and tried to connect again. Fantastic! It was connected.

Actually, this was not quite a troubleshooting but spent some time before I started the actual planned work. So I hope this will help someone to get things done easily without wasting time.