Got an error 'an exception of type 'system.nullreferenceexception' occurred in devexpress.dashboard.v16.2.core.dll but was not handled in user code'

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MVC

BI

DevExpress

C#7.0

I created Sample MVC devexpress Dashboard application.

I got an error 'An exception of type 'System.NullReferenceException' occurred in DevExpress.Dashboard.v16.2.Core.dll but was not handled in user code' while updating the data extract in gloabal.asax.cs.


void RegisterDefaultDashboard(string dashboardId)
{
string dashboardLocalPath = Server.MapPath(string.Format(@"~/App_Data/Dashboards/{0}.xml", dashboardId));
SessionDashboardStorage.Instance.RegisterDashboard(dashboardId, XDocument.Load(dashboardLocalPath));
ReloadExtract_Click(dashboardId);
}
protected void ReloadExtract_Click(string dashboardId)
{
using (Dashboard newDashboard = new Dashboard())
{
newDashboard.LoadFromXml(Server.MapPath(string.Format(@"~/App_Data/Dashboards/{0}.xml", dashboardId)));
var dataSources = newDashboard.DataSources.OfType<dashboardextractdatasource>().ToArray();
foreach (DashboardExtractDataSource dataSource in dataSources)
dataSource.UpdateExtractFile();
}
}

Please suggest me

What I have tried:

void RegisterDefaultDashboard(string dashboardId)
{
string dashboardLocalPath = Server.MapPath(string.Format(@"~/App_Data/Dashboards/{0}.xml", dashboardId));
SessionDashboardStorage.Instance.RegisterDashboard(dashboardId, XDocument.Load(dashboardLocalPath));
ReloadExtract_Click(dashboardId);
}
protected void ReloadExtract_Click(string dashboardId)
{
using (Dashboard newDashboard = new Dashboard())
{
newDashboard.LoadFromXml(Server.MapPath(string.Format(@"~/App_Data/Dashboards/{0}.xml", dashboardId)));
var dataSources = newDashboard.DataSources.OfType<dashboardextractdatasource>().ToArray();
foreach (DashboardExtractDataSource dataSource in dataSources)
dataSource.UpdateExtractFile();
}
}