Execution Timeout Expired. The timeout period elapsed prior to completion of the operation or the server is not responding.\r\nWarning: Null value is eliminated by an aggregate or other SET operation. code example

Example: execution timeout expired the timeout

using (SqlCommand sqlCmd = new SqlCommand(sqlQueryString, sqlConnection))
   {
      sqlCmd.CommandTimeout = 0; // 0 = give it as much time as it needs to complete
      ...
    }