Hello! I have spent hours googling for this error, but I can't find anything helpful to solve it.
I have a page with the Feedback module, and I get several of these errors on it every hour, clogging up my log.
I am hosting on Godaddy, and have several portals, but this is the only page that causes errors.
Any ideas on what I can try? Thanks! Alex

The log entry says:

Message: DotNetNuke.Services.Exceptions.PageLoadException: 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. ---> System.Web.HttpException: 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. ---> System.Web.UI.ViewStateException: Invalid viewstate. Client IP: 91.224.160.127 Port: 3941 User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; KKman2.0) ViewState: 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... --- End of inner exception stack trace --- at System.Web.UI.ViewStateException.ThrowError(Exception inner, String persistedState, String errorPageMessage, Boolean macValidati ) at System.Web.UI.ViewStateException.ThrowMacValidati (Exception inner, String persistedState) at System.Web.UI.ObjectStateFormatter.Deserialize(String inputString) at System.Web.UI.ObjectStateFormatter.System.Web.UI.IStateFormatter.Deserialize(String serializedState) at System.Web.UI.Util.DeserializeWithAssert(IStateFormatter formatter, String serializedState) 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) --- End of inner exception stack trace ---

Thank you for your reply. I am on GoDaddy so I have no control over the server farm.
I will upgrade to 6.2 and see if that helps. I wish I could tell it not to log those errors...

Could this be caused by having too many messages in the feedback? It currently displays page 1 of 10.

Thanks!
Alex

Well, I think something more nefarious is going on. One of the possibilities you pointed at was that a bot is trying to send email.
Since yesterday, this has been the activity:
8:04AM Client IP: 89.79.252.2 Port: 63712
6:44AM Client IP: 31.214.145.236 Port: 60487
5:26AM Client IP: 188.115.181.173 Port: 15532
5:06AM Client IP: 109.230.221.146 Port: 59303
5:06AM Client IP: 109.230.221.146 Port: 59295
4:26AM Client IP: 109.230.246.135 Port: 4655
3:27AM Client IP: 46.21.144.51 Port: 51157
1:38AM Application Started
1:23AM Application Started
12:30AM Client IP: 77.92.233.198 Port: 54356
12:30AM Client IP: 77.92.233.198 Port: 54356 (twice)
11:51PM Client IP: 188.143.233.160 Port: 1305
11:50PM Client IP: 91.224.160.126 Port: 3009
10:26PM Client IP: 109.230.221.146 Port: 58630

I really doubt that live people have been hitting that particular page that often to send me feedback...
It looks like I am under attack...
Alex