Catch a Sys.WebForms.PageRequestManagerServerErrorException that occurs when server is dow

Hello,

I have an ajax timer control that updates an update panel every couple of seconds. When/if the server is down, there is an error message in a popup that says

"Sys.WebForms.PageRequestManagerServerErrorException: An unknown error ocurred while processing the request
on the server. The status code reutrned from the server was: 12029"

Basically I want to be able to catch this exception so that the popup does not continue to occur.

Is this possible?

Thanks in advance.

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You can also use the PageRequestManager, for example (This code should be located on the client):

Sys.WebForms.PageRequestManager.getInstance().add_endRequest(EndRequestHandler);
function EndRequestHandler(sender, args)
{
if (args.get_error() != undefined)
{
var errorMessage;
if (args.get_response().get_statusCode() == '200')
{
errorMessage = args.get_error().message;
}
else
{
errorMessage = 'An unspecified error occurred. ';
}
args.set_errorHandled(true);
alert(errorMessage);
}
}

That's just what I needed. Thank you.

CascadingDropDown options is null or not an object

I have a couple of dropdown CascadingDropDown and the user is required to select an option from the first and then the second, and then click add. However, if they press add to fast, I get the error "'options' is null or not an object"

It's as if the the second dropdown is not full before the event is posted?!?!? Anyone know how I can prevent this?

Hi Poidda,

Based on my experience, to resolve this kind of issue we should make sure whether the problem is occurred on the client side or on the server side. Based on your description, I think your problem is likely occurred on the server side.

If it is a client issue, we suggest that you should keep the Button to be disabled until the last essential CascadingDropDown is selected. For example:

function pageLoad(){
$find("myCDEState").add_selectionChanged(onCCDSelected)
}
function onCCDSelected(){
//your other javascript code here.

$get("<%=Button.ClientID%>").disabled = false;
}

Otherwise , you should do some checking work on the server side. If it's null, return to the orignal page.

Best regards,

Jonathan

CascadingDropDown Method error 500

I have a couple of CascadingDropDown controls on an ASP.NET page and am filling them from a code behind function that makes a call to a SQL Server 2005 database. My problem is that sometimes I receive a 'Method error 500' when filling the second dropdownlist based on a parent control. I am concatenating three fields together and I can mix and match 2 of them, but when I use all three, I consistently get the error.

Example "Select StoreCode + ' ' + City + ' ' State as Name From Table".

Is there a data size limit with using this control?

Also, I am able to bind the same data to a dropdownlist not used in AJAX.

Thanks in Advanced,

Marc

I am encountering a similar problem with some CascadingDropDowns that help define someone's location. Whn I gt tothe City level, sometimes I get a 'Method Error 500' and sometimes I do not.

Your question "Is there a data size limit with using this control?" got me experimenting, and my results suggested that indeed there was a correlation between the error and the amount of data being returned.

So I installed IEInspector and fond that indeed, requests that return a lot of data are creating a problem. This is one of the responses I am getting:

{"Message":"Maximum length exceeded.","StackTrace":" at System.Web.Script.Services.RestHandler.InvokeMethod(HttpContext context, WebServiceMethodData methodData, IDictionary`2 rawParams)\r\n

at System.Web.Script.Services.RestHandler.ExecuteWebServiceCall(HttpContext context, WebServiceMethodData methodData)","ExceptionType":"System.InvalidOperationException"}

My next step is to use Reflctr to look at the code for System.Web.Script.Services.RestHandler.InvokeMethod and see what I discover.

Thanks for the data length suggestion!

Ken, thanks for the investigative work. Can you please keep me updated as to what you find?

I too will continue to debug this issue and will report any findings to this thread.

Thanks in advance,

Marc

Eureka!

Stepping thru the AJAX source code was tiring but informative.

In any event, here is my solution (if your underlying issue is different, YMMV).

I was hitting a size limit in the JSON conversion stuff, which fortunately can be customized without recompiling the code.

When returning custom objects (like the arrays returned by the CascadingDropDown web methods), the objects are serialized using object names, including their namespace. While my collections were only a few thousand items in length, the unfortunate choice of the long-winded namespace 'AjaxControlToolkit' and class name 'CascadingDropDownNameValue' results in ridiculous object bloat and blows out the default JSON string size by adding the long object name to every single object.

For example, a single City in my array of around 4000 of them is being returned like this:

"__type":"AjaxControlToolkit.CascadingDropDownNameValue","name":"Abanda","value":"2728903","isDefaultValue":false},{"

IMHO it would be much more efficient (and give us programmers less gray hairs!) if shorter names were used, like:

"__type":"AjaxCT.CDDNV","n":"Abanda","v":"2728903","def":false},{"

Or even better, instead of returning an array of objects, return a single object (thus avoiding the namespace.classname overhead in each array element) that contains a string with the data in it. That is exactly what I did in my earlier implementation using Michael Schwartz's AJAX.NET and my own custom code.

In any event, adding the following to my Web.Config solved my issues (so far):

<

system.web.extensions>
<scripting>
<webServices>
<jsonSerializationmaxJsonLength="5000000" />
</webServices>
</scripting>
</system.web.extensions>This link describes Web.Config settings for AJAX:

http://ajax.asp.net/docs/ConfiguringASPNETAJAX.aspx#microsoftweb

This forum thread was also helpful:

http://forums.asp.net/thread/1634922.aspx