Hi Joe,

After some testing on local and proprietary servers, I am now upgading to version 4.2.0.2. all sites under my administration, as it seems to solve some annoying issues of previous releases (localization of content editors, IE11 problems, etc.).

Nonetheless, I am still experiencing some IE11 problems (form submissions ignored etc.) working on sites hosted on the following webserver configuration (Aruba.it Provider):

mojoPortal Versione 2.4.0.2 MSSQL
Sistema Operativo Microsoft Windows NT 6.1.7601 Service Pack 1
Informazioni ASP.NET v4.0.30319 Esecuzione in 'Partial Trust'

One of these hosted sites does not allow the logon when using an IE11 (with Firexof and Chrome it works fine) and gives the following error:

Referrer(http://www.patriziasantoni.it/Secure/Login.aspx?returnurl=/) useragent Mozilla/5.0 (Windows NT 6.3; Trident/7.0; rv:11.0) like Gecko System.Web.UI.ViewStateException: Viewstate non valido. Client IP: 2.225.248.211 Port: 16029 Referer: http://www.patriziasantoni.it/Secure/Login.aspx?returnurl=%2f Path: /Default.aspx User-Agent: Mozilla/5.0 (Windows NT 6.3; Trident/7.0; rv:11.0) like Gecko ViewState: 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...

[ViewStateException: Viewstate non valido.
 Client IP: 2.225.248.211
 Port: 16408
 Referer: http://www.patriziasantoni.it/Secure/Login.aspx?returnurl=%2fDefault.aspx
 Path: /Default.aspx
 User-Agent: Mozilla/5.0 (Windows NT 6.3; Trident/7.0; rv:11.0) like Gecko
 ViewState: 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...]

[HttpException (0x80004005): Convalida di viewstate MAC non riuscita. Se questa applicazione è ospitata in una Web farm o in un cluster, verificare che la configurazione <machineKey> specifichi lo stesso validationKey e algoritmo di convalida. Impossibile utilizzare AutoGenerate in un cluster.]
   System.Web.UI.ViewStateException.ThrowError(Exception inner, String persistedState, String errorPageMessage, Boolean macValidationError) +235
   System.Web.UI.ViewStateException.ThrowMacValidationError(Exception inner, String persistedState) +14
   System.Web.UI.ObjectStateFormatter.Deserialize(String inputString) +274
   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() +241
   System.Web.UI.Page.LoadPageStateFromPersistenceMedium() +106
   System.Web.UI.Page.LoadAllState() +43
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +8431
   System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +253
   System.Web.UI.Page.ProcessRequest() +78
   System.Web.UI.Page.ProcessRequestWithNoAssert(HttpContext context) +21
   System.Web.UI.Page.ProcessRequest(HttpContext context) +49
   ASP.default_aspx.ProcessRequest(HttpContext context) +4
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +100
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +75

should I change anything in the config settings ?

Hi Joe,

I opened a support ticket with the hosting provider aruba.it and they came back with reference to these articles:

http://stackoverflow.com/questions/535366/viewstate-fails-in-ie-only
http://forums.asp.net/t/1960817.aspx?Click+ImageButton+under+Internet+Explorer+11+results+in+Viewstate+error

and suggested the following web.config change:

from this:

<pages validateRequest="false" viewStateEncryptionMode="Auto" maxPageStateFieldLength="500" controlRenderingCompatibilityVersion="4.0" clientIDMode="AutoID">

to this:

<pages enableEventValidation="false" viewStateEncryptionMode="Never" maxPageStateFieldLength="500" controlRenderingCompatibilityVersion="4.0" clientIDMode="AutoID" enableViewStateMac="false" >

The site seems now working and I can log in with IE11 but I wonder if this change could cause any lack of security

Regards
Diego