Thanks below are the complete deatils of error I allready clean the asp.net Temporary files. No relevant source lines] Source File: c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\opensearch\71fa1e73\e4433ca6\App_Web_ezvhodyz.2.cs Line: 0 Stack Trace: [FormatException: Invalid character in a Base-64 string.] 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: 7073 User-Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; GTB6.3; .NET CLR 2.0.50727; .NET CLR 3.0.04506.648; .NET CLR 3.5.21022; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729; InfoPath.2) 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 System.Web.UI.HiddenFieldPageStatePersister.Load() +217 System.Web.UI.Page.LoadPageStateFromPersistenceMedium() +105 System.Web.UI.Page.LoadAllState() +43 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +6785 System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean include