View PowerCLI: issue with 'get-desktopvm' cmdlet

Our application periodically makes remote powershell calls via wsman to the View connection broker to execute View PowerCLI cmdlets. We have noticed that wsman returns HTTP error code 500 for the execution of the cmdlet 'get-desktopvm', which coincides with the following message in the vCenter log of the vCenter that the broker is using.

The get-desktopvm cmdlet often succeeds, but once in a while, wsman would return error code 500.

(1)  Is there any correlation between get-desktopvm and the vCenter error message?
(2)  What is causing the vCenter error message?
(3)  What is causing the HTTP error code 500 to be returned by the wsman's execution of get-desktopvm?
(4)  What can be done to prevent these errors?

1. VirtualInfrastructure.Exceptions.ConnectionError: The request failed because the server '10.90.10.13' closed the connection. (The underlying connection was closed: A connection that was expected to be kept alive was closed by the server.)
2. System.Net.WebException: The underlying connection was closed: A connection that was expected to be kept alive was closed by the server.

Server stack trace:

   at System.Net.HttpWebRequest.EndGetResponse(IAsyncResult asyncResult)

Exception rethrown at [0]:

 

Thanks for any clarity