C# – Asp.net Invalid viewstate – Maybe IE8 4k dropped bug

I have been analyzing the data that I have been collecting and I have drawn a few conclusions. I noticed that a large majority of the errors that I have been getting are coming from windows Vista computers running IE 8 or Firefox 3. There where also a few cases where it was Vista and IE 7. This could explain why the errors are now just becoming an issue as more and more people are using the new operating system.

Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; FunWebProducts; .NET CLR 1.1.4322; .NET CLR 2.0.50727) Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; GoogleT5; MSN Optimized;CA; MSN Optimized;CA) Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.0; WOW64; Trident/4.0; GTB5; SLCC1; .NET CLR 2.0.50727; .NET CLR 3.0.04506; Media Center PC 5.0)

But anyways the conclusion that I want to get at is that based on this information I started looking into how the browsers process java scripts and if there was anything new that could be causing this issue, that’s when something interesting pop out at me, I found on the w3School website an article about the difference in html vs. xhtml.

Differences between HTML and XHTML HTML 4 and XHTML deal different with the content inside scripts:

In HTML 4, the content type is declared as CDATA, which means that entities will not be parsed. In XHTML, the content type is declared as (#PCDATA), which means that entities will be parsed. This means that in XHTML, all special characters should be encoded or all content should be wrapped inside a CDATA section.

To ensure that a script parses correctly in an XHTML document, use the following syntax:

So I immediately took a look into my code and I saw that the DOCTYPE directive was missing on some of my pages the sameones that are causing the Issue. I also noticed that where I was outputting JavaScript using the .NET Register Client Script routine it would wrap the inner content of the script tags with the CDATA attribute, while where there was the regular JavaScript written on the page there was no CDATA used. For example

I am no expert on how browser’s renders or parse the html return, but I strongly believe it has some thing to do with the situation above because the Url parameter in the Script Resource request whenever it crashes always contains code in between script tags that's below it. Some times there is even html style sheet code that can be found there as well. For example

http://braun.factoryoutletstore.com/ScriptResource.axd?d=70kBR-jPBTx9R89FxObjhipHPS9CMlta5W6ZZiqkaa5zNOXUU4DtsY8V_8function runSearchForField(eventObj, id){ if ((eventObj.which == 13) || (eventObj.keyCode == 13)) { var cat_gallery = getParam('gallery'); var cat = getParam('cat') var searchTerm = escape(document.getElementById(id).value); // must use escape() function to urlencode search term to avoid issues with '&' and '=' symbols var url; if (cat_

http://braun.factoryoutletstore.com/ScriptResource.axd?d=9vS7Hk65j_0hD8to_aPDj

Now what am thinking is that some how because am not specifying any DOCTYPE in the page the browser might be trying to infer based on the data its receiving then it ends up messing up because sometimes there is CDATA and there are times when there is no CDATA present in the page. I don’t know really if this is a solid assumption cause as they say assumptions as dangerous. If anyone can shade some light on my theory and let me know if the browsers are parsing the xhtml differently that older version or even if they had any similar situations.

I think these errors happen with different browsers for different reasons, which is what makes it so hard to track down.

IE8 Bug

Microsoft have said a bug in IE8 will (in some circumstances) generate spurious requests to the server, that do not affect the user but do lead to errors being logged at the server side.

See this discussion here: Bug IE8 – 4K dropped - "Invalid viewstate" when loading ScriptResource.axd (edit: link now requires login for some reason, sorry)

... particularly EricLaw-MSFT's update when he says:

It is worth mentioning that anyone who is experiencing a problem here in IE6/IE7 or Firefox is encountering a different problem that is not related to the IE8 issue described below.

This blog post also describes the bugs: Bugs in IE8's Lookahead Downloader

They say changing the way you set Content-Type will help with some of the errors, although not all of them - they say it is caused by various obscure circumstances that they are still looking at.

Update: As of 01/Apr/2010, these IE8 bugs have been fixed, via IE8 Cumulative Update (KB980182).
This post: IE8 Lookahead Downloader Fixed gives more detail on the bugs and other possible/partial workarounds (e.g this one) other than waiting for everyone in the world to download the fix.

Other Browsers

Haven't figured it out yet, but other browsers are also generating these errors, presumably for different reasons.

Web Farms

This problem is not restricted to sites running on web farms, but if you are running a farm, check out this answer by jesal which may help