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Posted 17 Aug 2012

My Experiences with the 'Sys is undefined' Javascript error

, 17 Aug 2012 CPOL
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This is an issue which can happen for a variety of reasons - but how do you find the right one?

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This is one of those issues which is tricky and can happen for a lot of reasons- and the troubleshooting process was very interesting. So I thought of sharing my experiences hacking this down.

The issue never happens on our development machines, and strangely it was happening only on one deployment machines [Windows Server 2008 R2, IIS 7.5,  .NET 3.5 and I.E 8]. 


We have a standard application with a few grids which are built using the Telerik RadGrid control.  

How do you notice the issue?<o:p /> 

-         None of the Telerik controls are working properly [Row selection, column selection navigation, etc does not work] 

-         On a page which has a Telerik control, you will see a “Done with errors” message on the status bar of IE (which we can easily miss)

If we happen to see the above javascript error and click on it, a popup will open up “Sys is undefined”

How do you go about the issue? 

A basic understanding of ASP.NET Ajax and ScriptManger controls will give you a hint on where to look. ASP.NET AJAX and Telerik controls rely on a lot of embedded resources (CSS, Javascript files, etc) that are dynamically loaded from an assembly at runtime. The ScriptManger or the RadScriptManager controls does exactly that. These controls rely on the webResource.axd http handler to do the job. Sys is the namespace of many classes of the AJAX related javascript files loaded at runtime. So obviously there was some problem loading the embedded resource. 

So this can happen if the webResource.axd is not doing its job correctly<o:p /> 

Now this is something very rare that can happen. So I looked at the HttpHandler section of the IIS > Default WebSite. The *.axd entry is there and is mapped to the right dll (aspnet_isapi.dll)

It may also happen if the web.config of our application is not properly configured for using ASP.NET Ajax. So I checked all those entries – everything looked fine. I also made sure that all the Telerik controls related web.confg sections are available. I even found a website that talk about this specific error and common resolutions. I tried all of them applicable, but nothing worked.

I checked the application log file, event log - nothing is logged. 

One of the sections in the above mentioned website talks about an authentication issue with RadScriptManager. Though, I added the proper authentication entries in the web.config, it still did not work. Then I thought of simply replacing the whole RadScriptManager control with a normal ScriptManager and give a try and BINGO! It worked. 

But the issue was still baffling me – RadScriptManger is close to a wrapper around the ScriptManager. Ideally if the later works, the former one should also work – unless there is some issue internally. But this would have easily manifested in the development machines as well. 

Enabling the Failed Request Tracing in IIS 

Now I thought of enabling the Failed Request Tracing in IIS. This will give me some hint on why a request has failed. We can enable this Failed Request Tracing in the IIS by following certain steps.

Once this was done I started getting log files in C:\inetpub\logs\FailedReqLogFiles. Looking at the log files, it was clearly stating that there was some issue requesting for Telerik.Web.UI.WebResource.axd, and strangely the error status code was 500 – which means that it crashed somewhere on the server side. When I looked for more details in the log file, it gave me more insight to the actual problem: 

[ArgumentOutOfRangeException: Specified argument was out of the range of valid values. Parameter name: utcDate] 

What this means there was some issue parsing a date which was passed as a query string parameter with the Telerik.Web.UI.WebResource.axd request. When I searched for this error, one of the telerik website said something like this: 

The assembly containing the embedded resources is probably built in the future (its last modified time is later than the current time). This can occur when deploying in a different time zone.”

This was strange - yes the deployment machine was in a different time zone, but how ever you calculate, I could have never built it in a future date compared to the Deployment machine!, how can this ever happen?! .. Unless the deployment machine time itself was wrong – I checked it and there it was - the time was set to 16-Aug-2011 instead of 16-Aug-2012! (I did the whole thing on 16th Aug 2012) 

I corrected the date on the machine and refreshed the page - the error was gone! 

<o:p />

Points of Interest 

While troubleshooting this problem, I was always convinced that it was some issue either in the IIS or the application web.config. I even thought it was some IE compatibility issue. Finally after getting the root of the issue, it just a simple date-time settings change in the deployment machine.




This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Abey Thomas
Technical Lead Philips
India India
I am Abey Thomas Raju from Bangalore, India.

More than 7 years of solid experience in designing, developing and maintaining web applications using .NET technologies.
Good knowledge of ASP.NET aspects and related web technologies like Javascript, AJAX, CSS and jquery.

Proven experience in Object oriented analysis and design by developing and maintaining top class back-end framework for successful financial web applications.

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Comments and Discussions

QuestionI don't think that is an article Pin
OriginalGriff16-Aug-12 20:23
mvpOriginalGriff16-Aug-12 20:23 
AnswerRe: I don't think that is an article Pin
Abey Thomas16-Aug-12 20:47
memberAbey Thomas16-Aug-12 20:47 
GeneralRe: I don't think that is an article Pin
OriginalGriff16-Aug-12 21:30
mvpOriginalGriff16-Aug-12 21:30 
AnswerRe: I don't think that is an article Pin
Abey Thomas16-Aug-12 22:03
memberAbey Thomas16-Aug-12 22:03 
GeneralRe: I don't think that is an article Pin
OriginalGriff16-Aug-12 22:21
mvpOriginalGriff16-Aug-12 22:21 
AnswerRe: I don't think that is an article Pin
Sandeep Mewara16-Aug-12 21:47
mvpSandeep Mewara16-Aug-12 21:47 

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