Received this error a day or two ago on website. It happened 3 times back to back within 2 minutes of each other. I have not seen this error before or since....and the same code is executed every day. (it is during login to website).

Any thoughts?

(ORMSupport - version 3.5.12.824, LinqSupport - version 3.5.12.807, self servicing)

System.NullReferenceException: Object reference not set to an instance of an object.
   at System.Object.GetType()
   at SD.LLBLGen.Pro.LinqSupportClasses.LinqUtils.ObtainRealValueFromConstantWrapped(MemberExpression expressionToHandle, Expression memberContainer)
   at SD.LLBLGen.Pro.LinqSupportClasses.ExpressionHandlers.PreProcessor.HandleMemberExpression(MemberExpression expressionToHandle)
   at SD.LLBLGen.Pro.LinqSupportClasses.ExpressionHandlers.GenericExpressionHandler.HandleExpression(Expression expressionToHandle)
   at SD.LLBLGen.Pro.LinqSupportClasses.ExpressionHandlers.PreProcessor.HandleInMemoryEvalCandidateExpression(InMemoryEvalCandidateExpression expressionToHandle)
   at SD.LLBLGen.Pro.LinqSupportClasses.ExpressionHandlers.GenericExpressionHandler.HandleExpression(Expression expressionToHandle)
   at SD.LLBLGen.Pro.LinqSupportClasses.ExpressionHandlers.GenericExpressionHandler.HandleBinaryExpression(BinaryExpression expressionToHandle)
   at SD.LLBLGen.Pro.LinqSupportClasses.ExpressionHandlers.PreProcessor.HandleBinaryExpression(BinaryExpression expressionToHandle)
   at SD.LLBLGen.Pro.LinqSupportClasses.ExpressionHandlers.GenericExpressionHandler.HandleExpression(Expression expressionToHandle)
   at SD.LLBLGen.Pro.LinqSupportClasses.ExpressionHandlers.GenericExpressionHandler.HandleBinaryExpression(BinaryExpression expressionToHandle)
   at SD.LLBLGen.Pro.LinqSupportClasses.ExpressionHandlers.PreProcessor.HandleBinaryExpression(BinaryExpression expressionToHandle)
   at SD.LLBLGen.Pro.LinqSupportClasses.ExpressionHandlers.GenericExpressionHandler.HandleExpression(Expression expressionToHandle)
   at SD.LLBLGen.Pro.LinqSupportClasses.ExpressionHandlers.GenericExpressionHandler.HandleLambdaExpression(LambdaExpression expressionToHandle)
   at SD.LLBLGen.Pro.LinqSupportClasses.ExpressionHandlers.GenericExpressionHandler.HandleExpression(Expression expressionToHandle)
   at SD.LLBLGen.Pro.LinqSupportClasses.ExpressionHandlers.PreProcessor.HandleMethodCallWhere(MethodCallExpression expressionToHandle)
   at SD.LLBLGen.Pro.LinqSupportClasses.ExpressionHandlers.PreProcessor.HandleQueryableExtensionMethod(MethodCallExpression expressionToHandle)
   at SD.LLBLGen.Pro.LinqSupportClasses.ExpressionHandlers.PreProcessor.HandleMethodCallPerType(MethodCallExpression expressionToHandle, Type declaringType)
   at SD.LLBLGen.Pro.LinqSupportClasses.ExpressionHandlers.PreProcessor.HandleMethodCallExpression(MethodCallExpression expressionToHandle)
   at SD.LLBLGen.Pro.LinqSupportClasses.ExpressionHandlers.GenericExpressionHandler.HandleExpression(Expression expressionToHandle)
   at SD.LLBLGen.Pro.LinqSupportClasses.ExpressionHandlers.PreProcessor.HandleMethodCallSelect(MethodCallExpression expressionToHandle)
   at SD.LLBLGen.Pro.LinqSupportClasses.ExpressionHandlers.PreProcessor.HandleQueryableExtensionMethod(MethodCallExpression expressionToHandle)
   at SD.LLBLGen.Pro.LinqSupportClasses.ExpressionHandlers.PreProcessor.HandleMethodCallPerType(MethodCallExpression expressionToHandle, Type declaringType)
   at SD.LLBLGen.Pro.LinqSupportClasses.ExpressionHandlers.PreProcessor.HandleMethodCallExpression(MethodCallExpression expressionToHandle)
   at SD.LLBLGen.Pro.LinqSupportClasses.ExpressionHandlers.GenericExpressionHandler.HandleExpression(Expression expressionToHandle)
   at SD.LLBLGen.Pro.LinqSupportClasses.ExpressionHandlers.PreProcessor.HandleMethodCallFirstSingle(MethodCallExpression expressionToHandle, Boolean isSingle, Boolean isDefault)
   at SD.LLBLGen.Pro.LinqSupportClasses.ExpressionHandlers.PreProcessor.HandleQueryableExtensionMethod(MethodCallExpression expressionToHandle)
   at SD.LLBLGen.Pro.LinqSupportClasses.ExpressionHandlers.PreProcessor.HandleMethodCallPerType(MethodCallExpression expressionToHandle, Type declaringType)
   at SD.LLBLGen.Pro.LinqSupportClasses.ExpressionHandlers.PreProcessor.HandleMethodCallExpression(MethodCallExpression expressionToHandle)
   at SD.LLBLGen.Pro.LinqSupportClasses.ExpressionHandlers.GenericExpressionHandler.HandleExpression(Expression expressionToHandle)
   at SD.LLBLGen.Pro.LinqSupportClasses.LLBLGenProProviderBase.HandleExpressionTree(Expression expression)
   at SD.LLBLGen.Pro.LinqSupportClasses.LLBLGenProProviderBase.Execute(Expression expression)
   at SD.LLBLGen.Pro.LinqSupportClasses.LLBLGenProProviderBase.System.Linq.IQueryProvider.Execute[TResult](Expression expression)
   at System.Linq.Queryable.FirstOrDefault[TSource](IQueryable`1 source)

Without the code that's executed, we can't say much... The call crashes in a reference to a member variable of the class the query is in. The expression tree will then contain a reference to an artificial type (e.g. <>_display ) and the local variable will be a member of it, which is then read with the code that crashes in your situation. It could be the object the member is part of is already gone, but I have no idea why that would occur / how that can be reproduced.

Ok, makes sense. I think one of the parameters was turning null (in a could not possibly happen situation - in theory) between the assign and the use in an asp.net web caching scenario.

I have made corrections on my end now that I understand exactly where the problem was.

Thanks.