The specific key is not a valid size for this algorithim

Dears, 

Since the latest update, I keep getting the below error whenever I try to edit the query. Please help. 

Thanks!

Unexpected error: The specified key is not a valid size for this algorithm.
Parameter name: key
Details:
    Microsoft.Mashup.Evaluator.Interface.ErrorException: The specified key is not a valid size for this algorithm.
Parameter name: key ---> System.ArgumentException: The specified key is not a valid size for this algorithm.
Parameter name: key ---> System.ArgumentException: The specified key is not a valid size for this algorithm.
Parameter name: key
   at System.Security.Cryptography.AesCryptoServiceProvider.CreateEncryptor(Byte[] key, Byte[] iv)
   at Microsoft.Mashup.EngineHost.Services.EncryptedPersistentCache.EncryptedStorage.EncryptPage(Byte[] input, Int32 count, Byte[] output)
   at Microsoft.Mashup.EngineHost.Services.TransformingPagedStream.WritePage(Int32 page, Byte[] buffer, Int32 length)
   at Microsoft.Mashup.EngineHost.Services.PagedStream.Flush()
   at Microsoft.Mashup.EngineHost.Services.EncryptedPersistentCache.EncryptedStorage.CommitStream(Int32 id, Stream stream)
   at Microsoft.Mashup.EngineHost.Services.WriteBehindPersistentCache.AsyncCommitStorage(String key, TemporaryStorage storage)
   at Microsoft.Mashup.EngineHost.Services.WriteBehindPersistentCache.AsyncCommitStorage(Object obj)
   at Microsoft.Mashup.Evaluator.EvaluatorThreadPool.EvaluatorThread(Object state)
   at Microsoft.Mashup.Evaluator.SafeThread2.<>c__DisplayClass15.<CreateAction>b__14(Object o)
   --- End of inner exception stack trace ---
   at Microsoft.Mashup.Evaluator.EvaluationHost.<>c__DisplayClass7.<TryReportException>b__6()
   at Microsoft.Mashup.Common.SafeExceptions.IgnoreSafeExceptions(IEngineHost host, IHostTrace trace, Action action)
   at Microsoft.Mashup.Evaluator.EvaluationHost.TryReportException(IHostTrace trace, IEngineHost engineHost, IMessageChannel channel, Exception exception)
   at Microsoft.Mashup.Evaluator.EvaluationHost.TryHandleException(Exception exception)
   at Microsoft.Mashup.Evaluator.SafeThread2.HandleException(Exception e)
   at Microsoft.Mashup.Evaluator.SafeThread2.<>c__DisplayClass15.<CreateAction>b__14(Object o)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ThreadHelper.ThreadStart(Object obj)
   --- End of inner exception stack trace ---
   at Microsoft.Mashup.Evaluator.EvaluationHost.OnException(IEngineHost engineHost, IMessageChannel channel, ExceptionMessage message)
   at Microsoft.Mashup.Evaluator.MessageHandlers.TryDispatch(IMessageChannel channel, Message message)
   at Microsoft.Mashup.Evaluator.MessageHandlers.Dispatch(IMessageChannel channel, Message message)
   at Microsoft.Mashup.Evaluator.ChannelMessenger.ChannelMessageHandlers.TryDispatch(IMessageChannel channel, Message message)
   at Microsoft.Mashup.Evaluator.MessageHandlers.Dispatch(IMessageChannel channel, Message message)
   at Microsoft.Mashup.Evaluator.ChannelMessenger.OnMessageWithUnknownChannel(IMessageChannel baseChannel, MessageWithUnknownChannel messageWithUnknownChannel)
   at Microsoft.Mashup.Evaluator.MessageHandlers.TryDispatch(IMessageChannel channel, Message message)
   at Microsoft.Mashup.Evaluator.ChannelMessenger.ChannelMessageHandlers.TryDispatch(IMessageChannel channel, Message message)
   at Microsoft.Mashup.Evaluator.MessageHandlers.Dispatch(IMessageChannel channel, Message message)
   at Microsoft.Mashup.Evaluator.Interface.IMessageChannelExtensions.WaitFor[T](IMessageChannel channel)
   at Microsoft.Mashup.Evaluator.RemotePreviewValueSource.PreviewValueSource.WaitFor(Func`1 condition, Boolean disposing)
   at Microsoft.Mashup.Evaluator.RemotePreviewValueSource.PreviewValueSource.get_TableSource()
   at Microsoft.Mashup.Evaluator.Interface.TracingPreviewValueSource.get_TableSource()
   at Microsoft.Mashup.Host.Document.Analysis.PackageDocumentAnalysisInfo.PackagePartitionAnalysisInfo.SetPreviewValue(EvaluationResult2`1 result, Func`1 getStaleSince, Func`1 getSampled)