Failed to load viewstate. The control tree into wh

问题:

I am receiving the following error message after an HTTP POST on an ASP.NET form hosted inside a UserControl:

Failed to load viewstate. The control tree into which viewstate is being loaded must match the control tree that was used to save viewstate during the previous request. For example, when adding controls dynamically, the controls added during a post-back must match the type and position of the controls added during the initial request.

Here's additional info:

• I'm running .NET 4.5 RC
• It's an Umbraco 4.7-based website
• On my local dev machine the form works perfectly
• This error only occurs on the staging server which has .NET 4.5 (only), MSSQL 2012 Express, IIS 7.5, Windows 7 (I know, it's not a real server yet, one day maybe...)
• The server is not part of a web farm (or garden, tho that should be irrevelant)
• The user control does render controls dynamically

I have applied all the latest service packs. I have run out of ideas now! I have even restarted it and also performed a richual over the server involving a song and a special dance to no avail.

回答1:

What is important when you are adding controls dynamically is on which event you are adding them.

If you added controls on events that occur after load, they will be part of the viewstate you send to the client.

You will have to add those controls again before LoadViewState is called.

If you run into cases where the decision of which controls to add is itself stored in the ViewState or the value of a control, then remember even before the ViewState is loaded, this data is available in Request.Params

Refer the asp.net page life cycle

回答2:

I just added EnableViewState="false" to my page placeholder and its gone. Hope it works for u as well.

回答3:

This Error Mainly Occurs during View state Change: From One Template To other Template like in case of Item Template, Edit Item Template, in Controls like Form View, List Views, Detail View, Grid View in ASP .net (all frameworks);

While Changing from control states say Item Template ---> Edit Template the followings were going to alter

1) Controls will change (its ID & states)

2) Its Positions will change.

While Transformation of view if any post back occurs you will get Error as

Failed to load viewstate. The control tree into which viewstate is being loaded....

if you are using separate control for data-binding like (button,link_button_Image_button events) you will get this error reported !

To avoid this error >>> Once state changes from one template to other within method you call data source binding ( Don't call during click or any post backing events ).

回答4:

OK, so the answer is literally: "Set up a new server with all the same software as the last one and try again" and it works now.

回答5:

I add "name" attribute with the same value as id, then this problem is gone.

<input type="button" id="extractBomInfoBtn" name="extractBomInfoBtn" value="Extract" class="button   textonly" />

回答6:

Check if you have the binding method of the control directly in your page load event. This can cause this problem.

回答7:

You can add new PlaceHolder per UserControls

OR

You can set enableviewstate=false on the control , if you dont need viewstate

回答8:

In my case I had a grid view with (OnPageIndexChanging) event and when I click on a page nothing will happen until I click it twice!

I was refreshing the data source before setting new page index.

---

This is what I was doing wrong

grd.DataSource = data;
grd.DataBind();
grd.PageIndex = e.NewPageIndex;

---

This is the right way

grd.PageIndex = e.NewPageIndex;
grd.DataSource = data;
grd.DataBind();

回答9:

I had the same issue. This issue was at client end but it didn't occur in my local system. After hours of googling, i had written EnableViewState="false" to my table tag in aspx page which has all the dynamic controls and then i removed all the viewstate variables and instead i created some hidden textboxes in the aspx page and accepted DB values into them in code behind and used them throughout my code. It then solved my problem. But still, i couldn't figure out what was exactly the problem.

回答10:

This can happen if you override SaveViewState in your control but don't override LoadViewState.