Server Error in '/' Application.

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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.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: 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.

Source Error:

[No relevant source lines]

Source File: App_Web_default.aspx.cdcab7d2.um3t8_ne.0... Line: 0

Stack Trace:

[HttpException (0x80004005): Unable to validate data.]

System.Web.Configuration.MachineKeySecti... buf, Byte[] modifier, Int32 start, Int32 length, Int32& dataLength) +2646292

System.Web.UI.ObjectStateFormatter.Deser... inputString) +214

[ViewStateException: Invalid viewstate.

Client IP: 65.34.193.236

Port: 4249

User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 2.0.50727; .NET CLR 1.1.4322)

ViewState: /wEPDwUKLTI3MTEzOTkxMQ9kFgJmD2QWAgIDD2QW...