Entity Framework - “Unable to create a constant value of type 'Closure type'…” error

Question

Why do I get the error:

Unable to create a constant value of type \'Closure type\'. Only primitive types (for instance Int32, String and Guid) are s

Answer 1

It looks like you're trying to do the equivalent of a "WHERE...IN" condition. Check out How to write 'WHERE IN' style queries using LINQ to Entities for an example of how to do that type of query with LINQ to Entities.

Also, I think the error message is particularly unhelpful in this case because .Contains is not followed by parentheses, which causes the compiler to recognize the whole predicate as a lambda expression.