What is the cause of the Linq.Expressions Expression<Func<T, bool>> error that occurs during a query with EF 7?

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The Linq.Expressions Expression<func<t, bool="">> error may occur during a query with EF 7 if the LINQ query expression contains syntax that is not supported by EF 7, or if the query is attempting to translate a method call or operator that EF 7 does not support. Additionally, the error may occur if the entity model used by the query does not match the SQL schema used by the database, or if there are other issues with the database connectivity or configuration.