NullReferenceException when using ReportViewer in MVC context

[Chris]

I'm using the ReportViewer control in the context of an MVC app, and have it setup as per an example that was provided on these forums, just like below.

This all works just great, until I deploy the application to production. When I access the application through its deployed URL, I get a yellow screen of death (although, it works if I log on to the web server locally). On the web server, the following log entry has been produced:
Event code: 3005 
Event message: An unhandled exception has occurred. 
Event time: 24/09/2012 17:53:02 
Event time (UTC): 24/09/2012 17:53:02 
Event ID: 1b93729293e4496bb55489a6a5febb04 
Event sequence: 333 
Event occurrence: 1 
Event detail code: 0 
 
Application information: 
    Application domain: /LM/W3SVC/1/ROOT/JobSystem.Mvc.csproj_deploy-1-129929735681023175 
    Trust level: Full 
    Application Virtual Path: /JobSystem.Mvc.csproj_deploy 
    Application Path: C:\inetpub\wwwroot\JobSystem.Mvc.csproj_deploy\ 
    Machine name: AMAZONA-NN5G6SK 
 
Process information: 
    Process ID: 3876 
    Process name: w3wp.exe 
    Account name: IIS APPPOOL\DefaultAppPool 
 
Exception information: 
    Exception type: NullReferenceException 
    Exception message: Object reference not set to an instance of an object.
   at Telerik.ReportViewer.WebForms.ViewerState.get_CurrentPage() in c:\temp\reporting\@RBuild-28250\Reporting_Build\Net20\Telerik.ReportViewer.WebForms\ViewerState.cs:line 123
   at Telerik.ReportViewer.WebForms.ReportPageOperation.RenderReport(String format, IList`1 processingReports, Hashtable deviceInfo, Hashtable renderingContext) in c:\temp\reporting\@RBuild-28250\Reporting_Build\Net20\Telerik.ReportViewer.WebForms\ReportPageOperation.cs:line 69
   at Telerik.ReportViewer.WebForms.ReportRenderOperation.PerformOperationOverride() in c:\temp\reporting\@RBuild-28250\Reporting_Build\Net20\Telerik.ReportViewer.WebForms\ReportRenderOperation.cs:line 79
   at Telerik.ReportViewer.WebForms.BasicHandler.ProcessRequest(HttpContext context) in c:\temp\reporting\@RBuild-28250\Reporting_Build\Net20\Telerik.ReportViewer.WebForms\HttpHandler.cs:line 191
   at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) 
 
Request information: 
    Request URL: http://development.intertekjobsys.com/JobSystem.Mvc.csproj_deploy/Telerik.ReportViewer.axd?instanceID=52255353489a40518fb367501fb9e5b7&optype=Report&PageIndex=0&RenderID=2722cd64754447ab82f6da5f52745be7&RenderingFormat=HTMLInteractive 
    Request path: /JobSystem.Mvc.csproj_deploy/Telerik.ReportViewer.axd 
    User host address: 10.248.22.26 
    User: [e-mail] 
    Is authenticated: True 
    Authentication Type: Forms 
    Thread account name: IIS APPPOOL\DefaultAppPool 
 
Thread information: 
    Thread ID: 10 
    Thread account name: IIS APPPOOL\DefaultAppPool 
    Is impersonating: False 
    Stack trace:    at Telerik.ReportViewer.WebForms.ViewerState.get_CurrentPage() in c:\temp\reporting\@RBuild-28250\Reporting_Build\Net20\Telerik.ReportViewer.WebForms\ViewerState.cs:line 123
   at Telerik.ReportViewer.WebForms.ReportPageOperation.RenderReport(String format, IList`1 processingReports, Hashtable deviceInfo, Hashtable renderingContext) in c:\temp\reporting\@RBuild-28250\Reporting_Build\Net20\Telerik.ReportViewer.WebForms\ReportPageOperation.cs:line 69
   at Telerik.ReportViewer.WebForms.ReportRenderOperation.PerformOperationOverride() in c:\temp\reporting\@RBuild-28250\Reporting_Build\Net20\Telerik.ReportViewer.WebForms\ReportRenderOperation.cs:line 79
   at Telerik.ReportViewer.WebForms.BasicHandler.ProcessRequest(HttpContext context) in c:\temp\reporting\@RBuild-28250\Reporting_Build\Net20\Telerik.ReportViewer.WebForms\HttpHandler.cs:line 191
   at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
 
Any ideas at all? This is virtually the last thing that I need to get working before I can put the app into production.

<%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage<Guid>" %>

<%@ Register Assembly="Telerik.ReportViewer.WebForms, Version=6.1.12.820, Culture=neutral, PublicKeyToken=a9d7983dfcc261be"

    Namespace="Telerik.ReportViewer.WebForms" TagPrefix="telerik" %>

<%@ Register Assembly="Telerik.Reporting, Version=6.1.12.820, Culture=neutral, PublicKeyToken=a9d7983dfcc261be"

    Namespace="Telerik.Reporting" TagPrefix="telerik" %>

<%@ Import Namespace="System.Web.Mvc" %>

<%@ Import Namespace="JobSystem.BusinessLogic.Services" %>

<%@ Import Namespace="JobSystem.Reporting.Data.NHibernate" %>

 

<!DOCTYPE html>

<html>

<head runat="server">

    <title>Consignment Note</title>

</head>

<body>

    <form id="main" method="post" action="">

        <telerik:ReportViewer ID="ReportViewer1" Width="100%" Height="800px" runat="server">

        </telerik:ReportViewer>

    </form>

    <script runat="server">

        public override void VerifyRenderingInServerForm(Control control)

        {

            //To avoid the server form (<form runat="server">) requirement

            //base.VerifyRenderingInServerForm(control);

        }

 

        protected override void OnLoad(EventArgs e)

        {

            base.OnLoad(e);

            var dataSource = new Telerik.Reporting.ObjectDataSource();

            dataSource.DataSource = typeof(NHibernateConsignmentReportDataProvider);

            dataSource.DataMember = "GetConsignmentReportData";

            dataSource.Parameters.Add(new Telerik.Reporting.ObjectDataSourceParameter("consignmentId", typeof(Guid), Model));

            var companyDetailsService = DependencyResolver.Current.GetService<CompanyDetailsService>();

            var report = new JobSystem.Reporting.ReportDefinitions.TelerikConsignmentReport();

            var company = companyDetailsService.GetCompany();

            System.Threading.Thread.CurrentThread.CurrentCulture = new System.Globalization.CultureInfo(company.DefaultCultureCode);

            var logo = companyDetailsService.GetCompanyLogo();

            var pageWidth = report.Width.Value;

            report.MainLogo.Value = logo;

            report.DataSource = dataSource;

 

            var instanceReportSource = new Telerik.Reporting.InstanceReportSource();

            instanceReportSource.ReportDocument = report;

            ReportViewer1.ReportSource = instanceReportSource;

        }

    </script>

</body>

</html>

The web.config like so:

<system.web>
<httpHandlers>
            <add type="Telerik.ReportViewer.WebForms.HttpHandler, Telerik.ReportViewer.WebForms, Version=6.1.12.820, Culture=neutral, PublicKeyToken=a9d7983dfcc261be" path="Telerik.ReportViewer.axd" verb="*" validate="true" />
        </httpHandlers>
<system.web>
<system.webServer>
        <validation validateIntegratedModeConfiguration="false" />
        <modules runAllManagedModulesForAllRequests="true" />
        <handlers>
            <add name="Telerik.ReportViewer.axd_*" type="Telerik.ReportViewer.WebForms.HttpHandler, Telerik.ReportViewer.WebForms, Version=6.1.12.820, Culture=neutral, PublicKeyToken=a9d7983dfcc261be" path="Telerik.ReportViewer.axd" verb="*" preCondition="integratedMode" />
        </handlers>
    </system.webServer>

[Chris]

Can any of the developers help with this?

[Steve]

Hello Chris,

Unfortunately we cannot reproduce such a problem in our local tests. Does the problem occur if you deploy the application in IIS on your dev machine? If yes, try to debug this further by turning on CLR exceptions .
The exception you get means that the report viewer cannot find the requested page, however, this should never happen because the pages are stored either in the ASP.NET Session (should be enabled for your application at all times) or as files. To track down the issue you can use an http debugging proxy like Fiddler to track requests and responses and see if you can get more info on the problem.
We would also suggest that you manually configure the Session State Management of our engine, so that the report pages and resources are cached in a single location e.g. in files by utilizing our File session provider. For more information please see Configuring the File Session State Provider. This way you can specify a folder where the rendered pages would be stored and you can observe in real time while navigating through the report, whether a requested page is present or not.

If the above suggestions do not yield any result, it will be best if you can send us a sample project that demonstrates the problem. Without it it will be very difficult to pinpoint the problem.

Regards,
Steve
the Telerik team

[Chris]

Hi,

First of all, I always use the local IIS on my dev machine, rather than the VS dev server. The problem is not reproducible on my development machine; it only occurs after being deployed on the server.

I have started the  ASP .NET State Service on the deployment machine, and made the web.config modifications as per this blog post. I also followed your instructions and enabled the File Session State Provider. When I log into server I can see a whole bunch of files being output in the location that I specified. The "page1" file looks to have all the relevant HTML content, and there are another 9 files that are named as GUIDs and look to have binary data in them.

Despite this, I still get the yellow screen of death and the exact same exception in the log. As per the last time, the report will also render just fine when I navigate to localhost on the deployment server.

You don't really get anything interesting from Fiddler, just a 500 error:
GET http://development.intertekjobsys.com/JobSystem.Mvc.csproj_deploy/Telerik.ReportViewer.axd?instanceID=01a14c9f213943478c4813e0f86d692e&optype=Report&PageIndex=0&RenderID=81ccdf7a4ee2416d88c13f6593eddff1&RenderingFormat=HTMLInteractive HTTP/1.1
Host: development.intertekjobsys.com
Connection: keep-alive
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.4 (KHTML, like Gecko) Chrome/22.0.1229.79 Safari/537.4
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Referer: http://development.intertekjobsys.com/Consignment/GenerateConsignmentNote/167506ea-c0d6-4e9b-b1e8-6f6618b0cc13
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-GB,en-US;q=0.8,en;q=0.6
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3
Cookie: ASP.NET_SessionId=s1oakmwhhbmfo42t2ahzxwhz; .ASPXAUTH=FDD66D141EF4675A880D14156A02A4BE1EDA1E740863621E523BE534CD0AC4D0319A1237C4BD13DE4B8AD349E013E641C109510D39A77FE7A06E3C00032777AF806AF5BC0569600DD0EB40245872340FB60C614C22FBA7BFCD08A48BBD45157A0449073E2151528D9CCAC81F598441C54CA8E2C0958378F35A552DA6F9ED7BFF21A41200

Could it be anything to do with that SessionId stuff? Since I'm an MVC person, having never really worked with classic ASP .NET, I don't really know anything about session state.

By a sample project, do you mean a small deployed project that reproduces the error? Maybe I could give you access to the server and then you could run a debug build and point it towards there, or something like that? That's all I could think to do, because the problem doesn't occur at all locally; therefore there would be no way for me to provide you with a sample project that reproduces the problem locally.

I am also really tight for time with this as we were hoping to have this application deployed this Monday.

Cheers,

Chris

[Chris]

One more thing.

This application has been deployed to Amazon Elastic Beanstalk.

There is some DNS related stuff going on, so that a domain name that I've registered redirects to the elastic beanstalk URL. However, the error occurs if I use the registered domain name or the Elastic Beanstalk URL directly.

Just letting you know, in case that could have anything to do with it.

[Steve]

Hello,

Thanks for the additional information.

After reading carefully your details, we can only assume the problem is related to the Amazon Web Services. We do not have an account there to review and test their offering, so we cannot really offer any concrete insight. The fact that it works on your IIS server, means that everything with your application and our software is in order and the problem must be specific to the hosting provider. From their site we see the following "Elastic Beanstalk automatically handles the deployment details of capacity provisioning, load balancing, auto-scaling", so we assume you're setting up your application to run in OutProc session correct? Have you tried setting cookieless attribute of the sessionState to true? Try configuring the session as cookieless in case session is not available there for some reason. Do you create multiple instances similar to Microsoft Azure? Have you tried to deploy with a single instance if so?

On a side note, if we open the URL you provided from Fiddler locally, we get an expected "Session has expired" error instead of NullReferenceException (see attached screenshot). Can you check the raw response in Fiddler to see if you would not find this same error in it? You can check the known reasons from the Report is unavailable or session has expired error message and see if you're not falling in one of the described scenarios.

Finally we see that this service from Amazon is still in Beta but could not find any listed limitations. Can you check up with them and verify that everything you need to run an application dependent on ASP.NET session is available to it? Additionally if they have some raw logs from their service that could bring more info, that would be great.

Greetings,
Steve
the Telerik team

[Chris]

Hi,

I'm going to reply in more detail later, but just to say briefly: it's a bit of a cop out to suggest that this has got something to do with AWS. All they're doing is providing Windows machines to host on, and there is nothing special about these servers as opposed to any others that exist independently of their hosting infrastructure. Even Elastic Beankstalk just uses vanilla Windows machines behind the scenes. The chances of there being anything wrong with respect to AWS will be virtually zero; it must be some configuration issue somewhere.

A quick Google shows that people seem to be getting on fine hosting ASP .NET stuff on EC2.

I'll try out the other suggestions regarding the session state stuff. As I say, this is an MVC application, the only aspect of it that has anything to do with ASP .NET is your reporting stuff. Since I've never had to concern myself with that, I don't really know much about it. I'll give those suggestions a try.

Cheers,

Chris

[Chris]

Hi,

I tried making the session state cookieless, but now I can't login to my application at all. I get a "webpage has resulted in too many redirects" error from the browser.

I know this has nothing to do with your reporting control, but is there any chance you could point me in the right direction with how to deal with this? I can't say whether or not the suggestion is going to work until I can actually access the application. Since this is an MVC app, it isn't using session state for anything except your reporting control.

Cheers,

Chris

[Steve]

Hello Chris,

To be thorough and not base our claims on guesses, we've gained access to Amazon Web Services and deployed an MVC application using Razor engine at Amazon Elastic Beanstalk. You can test it online at http://telerikreporting.elasticbeanstalk.com/. This is the same web application that is attached to the Using Telerik Web ReportViewer in ASP.NET MVC application code library, so you can test it on your account as well.

As you can see it works without any problems, we even tried it with cookieless="false" and did not encounter any errors (see attached screenshot). We've used default configuration for the Beanstalk (single instance) and have not changed anything. So if your application works fine, the problem must be related to the configuration of your deployed project.

Kind regards,
Steve
the Telerik team

[Chris]

Steve,

I actually already seen that sample project (telerikreportingaspnetmvc3vs2010.zip) several months ago, and indeed I have based my aspx files exactly off of that template.

Regarding the cookieless thing: you're only going to see problems with this if you have a non-toy application that actually requires you to login. Apparently, it seems as if cookieless might not be supported by MVC3 (see the bottom post), because going cookieless causes the URLs to become 'malformed' and difficult to deal with. If that's the case, the cookieless solution - which I've been unable to test anyway, since it breaks my application - isn't going to be a solution for me.

I have also tried it as a single instance - still no dice. In any case, I haven't changed anything at all regarding the Elastic Beanstalk setup; I'm simply using the out of the box settings.

Edit - when I say single instance there, I mean a single instance, still running in the context of Beanstalk. Admittedly I haven't yet tried it on a single machine, completely outwith the context of Beanstalk. I'm not sure how it would be different though, as when you run on Beanstalk with 1 instance, it's just using a Windows machine behind the scenes anyway.

I've been saying all along that it must be a configuration issue with the application; I need some help from you to try and find out what it is. I'm convinced it will be something to do with the configuration of the application itself rather than any nuances with a particular hosting environment such as Beanstalk. I could even give you access to the web servers where it's running, if that would be of any use. Or copies of my web.config, or anything else you might find useful.

Cheers,

Chris

[Massimiliano Bassili]

Chris,

Although this is the right place to ask for help, I see that telerik have already said they cannot reproduce the problem locally, so just repeating your observations from day one even after you've been presented with a runnable test seems like a waste of time and breath to me. I would do:

1. Involve amazon support on this one.
2. Provide your full project to telerik, so they can debug it.

It does not really make sense to me, to be a configuration issue of the application, otherwise why would it work on your machine? Deploy it on another machine for the test, if it works there, then do the math and point fingers somewhere else.

[Chris]

"It does not really make sense to me, to be a configuration issue of the application, otherwise why would it work on your machine?"
I have to respectfully disagree with you there: things happen all the time when you move from your dev environment to production. Generally this is due to configuration problems, such as things missing on the production server that you didn't even realise you had in the dev environment. In this specific case: I wasn't even using the ASP .NET State Service in the development environment. There are a myriad of things like this that occur when you move into production.

Btw, your demo app doesn't seem to be free of the session expiry problem; I've attached a screenshot.

Anyway, putting all of that aside, I've at least made some progress in isolating/reproducing the problem.

I completely cleared out the Beanstalk application and started a new one, with only a single machine on the load balancer. Everything was working completely fine with that; no errors at all, with any reports. I should add, that was using an out of the box machine, with no special services or anything added. I was using your file session state provider, rather than having the state service switched on.

As soon as I added another machine to the load balancer, the error started to occur. The idea is that new machines are supposed to be able to come online when you're under heavy load, so I need to get this scenario working. Even after you restart both the app servers when you're running 2 machines, the error still occurs.

It is also the same if you're starting from scratch and both the machines have the state service turned on - I tried that too.

I know that you might say to me that the problem lies with AWS here, and you may even be right. I'm still not convinced that it does; however, in any case, I have to say to you honestly, I don't really know how to approach Amazon with such a problem. After all, the 2nd machine is just an image of the 1st one: the idea is that a request should be able to go to any machine on the load balancer, with the same result. I've got a feeling that if I went to them (and all that they have is forums btw, I don't think you get official support tickets) with a stack trace from your code, they would just refer me back to you, and then I'm stuck in a circular loop. 

At least for the time being I can run the application just on a single machine, but it's not a viable long term solution.

Can you see if you can reproduce the problem by adding a 2nd machine to your environment?

Regarding getting the code for my project, you can clone it in git:
git clone https://github.com/chrisoneil/JobSystem.git
git fetch
git checkout -b development origin/development

Any feedback from these recent findings would be appreciated.

Cheers,

Chris

[Chris]

I'm working on this project freelance as a way to earn some extra money, but I also work a day job for a professional software company. One of my colleagues said this morning "could it be something to do with sharing view state between 2 different machines?" I believe that the State Service uses file system storage behind the scenes? And so the file system is obviously local to each server. Could it be, for that reason, that this scenario might not be supported at all over multiple machines?

Does that make any sense to you? None of us know very much about aspx stuff.

[Chris]

Another colleague has suggested "sticky sessions" could be the problem. I wasn't even aware of the concept until now.

Looks like there is a setting on the load balancer for this: hopefully that might resolve the issue. Don't have time to test at the moment.

[Steve]

Hello Chris,

Thank you for sharing your additional findings, we would definitely verify if enabling multiple instances breaks Telerik Reporting. In fact we would have tested by now, but it seems that any configuration change, renders the running git version corrupted and we have to redeploy.
I also saw the setting for Enabling Sticky Sessions and we believe this might be a possible solution.

We also believe that switching entirely to Memory cache should resolve such problems. Please see Configuring Session State for explanations.

Kind regards,
Steve
the Telerik team

[Carl]

What was the resolution for this? We are having the same issue and using sticky sessions is not a preferred solution for us. We have tried Memory cache and File cache that points to a shared file location, but we continue to get the NullReferenceException. What do we need to do to get the Telerik Reports working with two web servers behind a load balancer?

Thanks.

[Stef]

Hi Carl,

In order Telerik Reporting ASP.NET ReportViewer to work with load balancing methods, you need to configure the cache and the access to it. Also the create reports and used data should follow the rules listed in the Design Considerations for Out-proc Session State help article.

More details about the causes of the issue are listed in the Report is unavailable or session has expired error message KB article.

Note that as of Q3 2013 we released new HTML5 Report Viewer, which does not rely on the ASP.NET Session and may suit better your requirements.

Regards,
Stef
Telerik

[Carl]

Hi Stef,

Thanks for your response. I would prefer to use the new HTML5 Report Viewer than make additional changes to make it work in the ASP.NET ReportViewer. I am having a hard time finding documentation that details the process of utilizing my reports that I've created for the ASP.NET ReportViewer in the new HTML5 Report Viewer. Is that possible? Does such documentation exist?

Thanks,
Carl

[Stef]

Hello Carl,

The supported by default report sources are TypeReportSource (ReportTypeResolver) and UriReportSource (ReportFileResolver). If you need other implementation, you can create custom Report Resolver and load the report you need.

I hope this helps you.

Regards,
Stef
Telerik

[Magzhan]

Unknown build error, 'Could not load file or assembly'Telerik.OpenAccess, Version=2015.1.220.1, Culture=neutral, PublicKeyToken=7ce17eeaf1d59342' or one of their dependencies. Can not find the file specified.

[Stef]

Hi Magzhan,

Please check if you have a reference or copy in the BIN folder of Telerik.Reporting.Cache.Database.dll.
This assembly is required if you have enabled the database cache for a viewer (not applicable for the HTML5 Viewer) .

for more details, check Configuring the Database Cache Provider and Telerik Data Access Dependencies.

If database cache is not a used feature in the project, you can remove the assembly. If you are using the cache feature, you will need to add Telerik Data Access assemblies via Nuget packages, and then to verify that binding redirects are added in the application's configuration file.

Regards,
Stef
Telerik