Problem: Recently we have installed the SQL Server 2008 Reporting Service on the Windows Server 2008. Reporting Service installed and configured successfully but while browsing the http://servername:80/reports it is getting failed with the error HTTP 500. Below error recoded into the Reporting Service Error log.

Unable to validate data. at System.Web.Configuration.MachineKeySection.GetDeco dedData(Byte[] buf, Byte[] modifier, Int32 start, Int32 length, Int32& dataLength) at System.Web.UI.ObjectStateFormatter.Deserialize(Str ing inputString)

Solution:

It looks reason for the above error is two different encryptions (FIPS and AES) and decryption algorithm is trying to do the validation and because of that reporting service is unable to load the reporting service URL. I have resolved the issue by following the below steps.

Reporting Service will fail to load if any of the below condition will be true.

The HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa\fipsalgorithmpolicy registry value is set to 1.

ASP.NET 2.0 uses the RijndaelManaged implementation of the AES algorithm when it processes view state data

You can follow one of the below fix. Either disable the FipsAlgorithmPolocy or add the mentioned machine key into the web.config file. Browse the path HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa\fipsalgorithmpolicy and changed value 1 to 0.

Open the reporting service web.config file and add the below <machinekey> into <system.web> section.

<machineKey validationKey=”AutoGenerate,IsolateApps” decryptionKey=”AutoGenerate,IsolateApps” validation=”3DES” decryption=”3DES”/>

Next step is to restart the reporting service and IIS. You can restart the IIS using IISRESET command and reporting service using NET START/STOP command.

NET STOP “SQL Server Reporting Services (MSSQLSERVER)”

NET START “SQL Server Reporting Services (MSSQLSERVER)”