MS SDK - Validation of viewstate MAC failed

[tarasklimenko]

Description:

The MS SDK Webhooks sample app throws an error when attempting to get notifications after a period of time.

Below is the stack trace:

[ViewStateException: Invalid viewstate. 
    Client IP: 50.149.116.161
    Port: 57109
    Referer: https://wdev.code-api-att.com/webhook/Default.aspx?code=BF-ACSI%7e4%7e20150302220353%7ekcM9C5BU98k1rPS97bb9
    Path: /webhook/Default.aspx
    User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/40.0.2214.115 Safari/537.36
    ViewState: /wEPDwUKLTI4NjY2MTEzMA9kFgICAg9kFgoCAQ8PFgIeBFRleHQFHk1vbiwgTWFyIDAyLCAyMDE1IDIyOjA0OjUxIFVUQ2RkAhkPPCsAEQIADxYEHgtfIURhdGFCb3VuZGceC18hSXRlbUNvdW50ZmQBEBYAFgAWAGQCJQ8PFgIeB1Zpc2libGVoZBYCAgUPPCsAEQBkAi8PDxYCHwNoZGQCMQ8PFgIfA2hkZBgCBRBndk1lc3NhZ2VIZWFkZXJzD2dkBQlndkRldGFpbHMPPCsADAEIZmT1bkQ732JsZCaVLZXbiXZskj1/zqWEbqbGlrbT3uVoVg==]

[HttpException (0x80004005): Validation of viewstate MAC failed. If this application is hosted by a Web Farm or cluster, ensure that <machineKey> configuration specifies the same validationKey and validation algorithm. AutoGenerate cannot be used in a cluster.

http://go.microsoft.com/fwlink/?LinkID=314055]
   System.Web.UI.ViewStateException.ThrowError(Exception inner, String persistedState, String errorPageMessage, Boolean macValidationError) +169
   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() +219
   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.webhook_default_aspx.ProcessRequest(HttpContext context) in c:\windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files\root\219c23b3\42a24ab9\App_Web_u3btnjco.2.cs:0
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +100
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +75

Actual:

The SDK times out after a period of time and throws the error above.

Expected:

It's expected for the app to run continuously without interruption. Allowing user to get notifications 24 hours a day.

Repro:

1. Create Notification Channel via MS SDK Webhooks Sample App
2. Subscribe to Channel
3. Get Notifications via Subscription to Channel
4. Wait for a period of time (not determined)
5. Notice error is thrown (shown above)

[junhuac]

This is a known issue when IIS is deployed in cloud:

https://msdn.microsoft.com/en-us/library/ff649308.aspx

I have generated machine keys for WDEV. The ViewState error should be fixed now.