Hi all,

A problem has just started occuring, whenever I create or change a document type I now get:

The state information is invalid for this page and might be corrupted.Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.Web.HttpException: The state information is invalid for this page and might be corrupted.

Source Error: 

[No relevant source lines]





Source File: c:\Windows\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\root\85ac1099\66376fb3\App_Web_editnodetypenew.aspx.a5729980.qfkcd-zy.0.cs    Line: 0 

Here's the first few lines from the stack trace:

[FormatException: Invalid length for a Base-64 char array.]
   System.Convert.FromBase64String(String s) +0
   System.Web.UI.ObjectStateFormatter.Deserialize(String inputString) +72
   System.Web.UI.ObjectStateFormatter.System.Web.UI.IStateFormatter.Deserialize(String serializedState) +4
   System.Web.UI.Util.DeserializeWithAssert(IStateFormatter formatter, String serializedState) +37
   System.Web.UI.HiddenFieldPageStatePersister.Load() +113

[ViewStateException: Invalid viewstate. 
    Client IP: 127.0.0.1
    Port: 61060
    User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US) AppleWebKit/533.4 (KHTML, like Gecko) Chrome/5.0.375.99 Safari/533.4
    ViewState: 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...]

[HttpException (0x80004005): The state information is invalid for this page and might be corrupted.]
   System.Web.UI.ViewStateException.ThrowError(Exception inner, String persistedState, String errorPageMessage, Boolean macValidationError) +106
   System.Web.UI.ViewStateException.ThrowViewStateError(Exception inner, String persistedState) +14

Any ideas what could be causing this? The problem is pretty severe for me as it is preventing me working on my project.

Thanks for your help.