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