TaskContinuation.cs not found exception while accessing WebAPI Task - asp.net-web-api

Question

I'm trying to fetch records from a db cursor from the Client app.
Debugging Web API shows that the Cursor returns records but when returning to the Client it throws mscorlib.pdb not loaded window and clicking on Load option it throws TaskContinuation.cs not found exception
Code snippets as below ( removed irrelevant codes for readability )
WebAPI
[HttpPost("{values}")]
public async Task<ActionResult> Post([FromBody] JToken values)
{
// code removed for readility
string[] cursors = { };
cursors = await cursor.GetRpts();
CursorClass firstCursor = JsonConvert.DeserializeObject<CursorClass>(cursors[0]);
return new OkObjectResult(cursors);
}
public async Task<string[]> GetRpts()
{
try
{
DataTable[] dataTables;
CursorClass[] cursorClasses = new CursorClass[5];
//stripped some code
using (DataAccess dataAccess = new DataAccess()
{
ParamData = PrepareDoc(),
ProcedureName = Constants.Rpt,
RecordSets = this.CursorNumbers,
})
{
Int32 errorNumber = await dataAccess.RunComAsync();
dataTables = dataAccess.TableData;
};
//fetching code stripped off
string[] _cursors = Array.ConvertAll(cursorClasses, JsonConvert.SerializeObject);
return _cursors;
}
catch (Exception ex)
{
string tt = ex.Message;
}
}
public async Task<Int32> RunComAsync()
{
Int32 returnValue = 0;
try
{
//open db connection
//---------- Running the Command in asysnc mode ----------
Task<int> task = new Task<int>(oracleCommand.ExecuteNonQuery);
task.Start();
returnValue = await task;
//--------------------------------------------------------
OracleRefCursor[] refCursor = { null, null, null, null, null };
for (int _sub = 0; _sub < RecordSets; _sub++)
{
//DT declaration / connection code removed
dataAdapter.Fill(dataTable, refCursor[_sub]);
TableData[_sub] = dataTable;
}
}
catch (Exception ex)
{
return LogMsg(ex);
}
finally
{
this.Dispose(true);
}
CloseConnection();
return LogMsg(null,"Successful Operation");
}
Client
private async Task<HttpStatusCode> CallService()
{
HttpResponseMessage _response = null;
try
{
using (HttpRequestMessage requestMessage = new HttpRequestMessage()
{
Content = new System.Net.Http.StringContent(JsonRepo, System.Text.Encoding.UTF8, HeaderJson),
RequestUri = new Uri(UriString),
Method = HttpMethod.Post,
})
{
requestMessage.Headers.Authorization = new AuthenticationHeaderValue("Bearer", Utils.TOKEN) ;
_response = await httpClient.SendAsync(requestMessage);
if (_response.IsSuccessStatusCode)
{
string httpResponse = await _response.Content.ReadAsStringAsync();
httpString = JsonConvert.DeserializeObject<string[]>(httpResponse);
}
}
}
return ErrorCode;
}
Is that something related to async operation? while debugging the API it confirms the Datatable with records . Any inputs are deeply appreciated.
error image
TIA