Unable to create calender event via rest using UserApiKeys

Hi ,

We are trying to create calender event using UserApiKeys from webrequest api.ashx/v2/calendars/121/events.json , we are able to find below Exception 

Telligent.Evolution.Extensibility.Rest.Infrastructure.Version1.RestException: Unknown: An unexpected error prevented your requested action from completing. The error has been logged for the administrator to review.
   at Telligent.Evolution.Calendar.Plugins.RestApi.EventRestEndpoints.Create(IRestRequest request)
   at Telligent.Evolution.Rest.Framework.Infrastructure.RestPluginHttpHandler.ProcessRequest(HttpContextBase context, HttpResponse httpResponse)

we are on 10.3.0.6491

Edited
[edited by: Satish Kumar Polampalli at 1:20 PM (GMT 0) on Wed, Apr 29 2020]