[SOLVED] System.Web.UI.ViewStateException ,Invalid viewstate

System.Web.UI.ViewStateException ,Invalid viewstate

My website is throwing the below exceptions everyday and i couldn't find the solution. i did few research in web and this is what i do so far. adding below option to aspx won't solve the problem.

ValidateRequest="false" EnableEventValidation="false" ViewStateEncryptionMode="Never" EnableViewStateMac="false"

Also, my Referral Url is the correct URL and i have no idea how it redirect with two (same) parameters. there is no such link in my referral page. Please help.

ERROR LOG

URL : http://www.abcd.com/company-details.aspx?com=asia-pacific-pte-ltd&com=asia-pacific-pte-ltd

referral URL : http://www.abcd.com/companies/asia-pacific-pte-ltd/

Inner Exception Type: System.Web.UI.ViewStateException

Inner Exception: Invalid viewstate. Client IP: 192.162.19.193 Port: 1966 User-Agent: Opera/9.80 (Windows NT 6.1; WOW64; MRA 6.0 (build 6001)) Presto/2.12.388 Version/12.11 ViewState: 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...

Inner Source: 

Exception Type: System.Web.HttpException

Exception: The state information is invalid for this page and might be corrupted.

Stack Trace: at System.Web.UI.ViewStateException.ThrowError(Exception inner, String persistedState, String errorPageMessage, Boolean macValidationError) at System.Web.UI.HiddenFieldPageStatePersister.Load() at System.Web.UI.Page.LoadPageStateFromPersistenceMedium() at System.Web.UI.Page.LoadAllState() at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) at System.Web.UI.Page.ProcessRequest() at System.Web.UI.Page.ProcessRequest(HttpContext context) at ASP.exhibition_details_aspx.ProcessRequest(HttpContext context) in c:\Windows\Microsoft.NET\Framework64\v2.0.50727\Temporary ASP.NET Files\root\0f461847\442b0502\App_Web_bfjqxdef.20.cs:line 0 at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

UPDATE i have fixed the error by compressing the ViewState from below link http://www.codeproject.com/Articles/14733/ViewState-Compression

and fixed the Invalid length for a Base-64 char array error by replacing the original method with this.

protected override object LoadPageStateFromPersistenceMedium()
    {
        string viewState = Request.Form["__VSTATE"];
        viewState = viewState.Replace(" ", "+");

        int mod4 = viewState.Length % 4;
        if (mod4 > 0)
        {
            viewState += new string('=', 4 - mod4);
        }
        byte[] bytes = Convert.FromBase64String(viewState);
        bytes = Compressor.Decompress(bytes);
        LosFormatter formatter = new LosFormatter();
        return formatter.Deserialize(Convert.ToBase64String(bytes));
    }

Thanks everyone for help :)

Solution