Hello,

I'm trying to debug a problem that we see in production with partial page postbacks on a page that also has hidden webdialog windows on it.

I did a stack trace and I saw that I have Infragistics Javascript code in the call stack:

Here is the call stack, it's blowing up when it's calling c.apply(a), because c is null.

return c.apply(a);                                                      //MicrosoftAjax.js
$IG.Header.callBaseMethod(this, 'dispose');    //Infragistics stuff
this._header.dispose();                                         //Infragistics stuff
a.control.dispose();                                                //MicrosoftAjaxWebForms.js
this._destroyTree(updatePanelElement);         //MicrosoftAjaxWebForms.js
this._updatePanel(j, n)                                         //MicrosoftAjaxWebForms.js
return b.apply(a, arguments)                              //MicrosoftAjax.js                        ***
c(this)                                                                       //MicrosoftAjax.js
this._loadScriptsInternal()                                     //MicrosoftAjax.js
return b.apply(a, arguments)                              //MicrosoftAjax.js                        ***
b._completedCallback(a, true)                             //MicrosoftAjax.js

The web dialog isn't being used when the partial page postback is occurring, it's hidden, but it is inside the update panel that's being re-rendered.  The error happens when the user gets moved to a new server on the web server farm. 

Since it's happening when the page is being returned by a different server in the web farm, I suspect it's viewstate related.  I've triple checked and all the servers in the farm are using the same machineKey. 

In addition to this, and I suspect in relation to this, I see that when I have the Infragistics web dialog control is on my page; the viewstate appears to be invalid.  Various viewstate rendering tools are incapable of deciphering it.  I created a version of my page without the Infragistics web dialog controls, but keeping everything else including my update panel, and the viewstate rendering tools can display a tree structure of my viewstate just fine.

Thanks,

Eric