Problem with the multiple report

Hi,

We use the Web AppBuilder App to host reports. 

When selecting multiple objects (two and more) by the ESRI Select widget the report download ends with this error:

{

 "error": {

  "id": "GR001.400",

  "message": "GR001.400: Bad Request",

  "status": 400

 },

 "log": {

  "start": "2019-02-04T14:26:09.7814145Z",

  "end": "2019-02-04T14:26:09.8064098Z",

  "traces": [

   "Error: 0: Unexpected Error: System.ArgumentNullException: Value cannot be null.",

   "Parameter name: value",

   "  at Geocortex.Reporting.Platforms.FileStoreClient.<LookupAsync>d__26.MoveNext()",

   "--- End of stack trace from previous location where exception was thrown ---",

   "  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()",

   "  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)",

   "  at Geocortex.Reporting.Foundation.Helpers.<ReadFirstAsync>d__11`1.MoveNext()",

   "--- End of stack trace from previous location where exception was thrown ---",

   "  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()",

   "  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)",

   "  at Geocortex.Reporting.Http.ServiceController.<FindResultAsync>d__36.MoveNext()",

   "--- End of stack trace from previous location where exception was thrown ---",

   "  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()",

   "  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)",

   "  at Geocortex.Reporting.Http.ServiceController.<FetchAsync>d__37.MoveNext()",

   "--- End of stack trace from previous location where exception was thrown ---",

   "  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()",

   "  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)",

   "  at System.Threading.Tasks.TaskHelpersExtensions.<CastToObject>d__3`1.MoveNext()",

   "--- End of stack trace from previous location where exception was thrown ---",

   "  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()",

   "  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)",

   "  at System.Web.Http.Controllers.ApiControllerActionInvoker.<InvokeActionAsyncCore>d__0.MoveNext()",

   "--- End of stack trace from previous location where exception was thrown ---",

   "  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()",

   "  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)",

   "  at System.Web.Http.Controllers.ActionFilterResult.<ExecuteAsync>d__2.MoveNext()",

   "--- End of stack trace from previous location where exception was thrown ---",

   "  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()",

   "  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)",

   "  at Geocortex.Reporting.Http.BaseController.<>c__DisplayClass41_0.<<ExecuteCoreAsync>b__0>d.MoveNext()"

  ]

 }

}

When selecting only one object the report is OK.

Our configuration:

Geocortex Reporting 5.2.0 on premises

Portal for ArcGIS 10.6

Thanks for any advice,

Marek