Validation of ViewState MAC failed

[daveh551]

Okay, I've googled this, and come up with several articles, but none
of them seem to apply to my site.

I have an eCommerce site with a product category tree in the left
navigation bar. The tree is build using a TreeView control, and a
SiteMap navigation data source. While I normally disable ViewState
whenever possible, it HAS to be on for the TreeView to work, or it
doesn't change state when the user expands and collapses nodes. There
are a fairly large number of nodes (around 60 fully expanded), so the
ViewState is fairly massive (it takes up an entire Notepad screen plus
a little when I do a View Source on the displayed page.)

Here's the problem: When I run the site in IE (but not in FireFox),
and click on one of the categories to navigate to it (though not just
to expand or collapse it), It throws a "Validation of ViewState MAC
failed." Needless to say, I am not running on a Server Farm, and I am
giving plenty of time for the page to fully load, and I am not using
DataKeyNames (some of the common threads I have found running through
the articles I have found.)

Any clues? FWIW, it's running the 2.0 framework under VS 2005,
running IE 7.0. It works fine with Firefox. It fails under the
debugger, and, much to my chagrin, on the production site as well.

Thanks for your help.

[daveh551]

On Aug 19, 10:45*pm, daveh551 <[e-mail]:

Okay, I've googled this, and come up with several articles, but none
of them seem to apply to my site.

I have an eCommerce site with a product category tree in the left
navigation bar. The tree is build using a TreeView control, and a
SiteMap navigation data source. *While I normally disable ViewState
whenever possible, it HAS to be on for the TreeView to work, or it
doesn't change state when the user expands and collapses nodes. *There
are a fairly large number of nodes (around 60 fully expanded), so the
ViewState is fairly massive (it takes up an entire Notepad screen plus
a little when I do a View Source on the displayed page.)

Here's the problem: When I run the site in IE (but not in FireFox),
and click on one of the categories to navigate to it (though not just
to expand or collapse it), It throws a "Validation of ViewState MAC
failed." *Needless to say, I am not running on a Server Farm, and I am
giving plenty of time for the page to fully load, and I am not using
DataKeyNames (some of the common threads I have found running through
the articles I have found.)

Any clues? *FWIW, it's running the 2.0 framework under VS 2005,
running IE 7.0. *It works fine with Firefox. *It fails under the
debugger, and, much to my chagrin, on the production site as well.

Thanks for your help.

Never mind, I solved it. I had copied in some HTML from another
source without really understanding it, and had included a <form>
element nested within the <formcreated by ASP.NET. Apparentlyly, IE
gets more bent out of shape about that than Firefox does. Changing
the nested <formto a <divmade the problem go away.