Entity framework exists clause with lambda - entity-framework

Question

I've seen an answer to a similar problem (Entity framework and Exists clause), but not using lambda and I would like to understand what is wrong,
whether it is my mapping or if is the way to use. I'm using Entity Framework 5.
Here is my mapping:
public class Attribute : EntityWithGuid
{
... Other mappings ....
[InverseProperty("Attribute")]
public virtual ICollection<CategoryAttribute> CategoryAttributes { get; set; }
}
public class Category : EntityWithGuid
{
... Other mappings ....
[InverseProperty("Category")]
public virtual ICollection<CategoryAttribute> CategoryAttributes { get; set; }
}
public class CategoryAttribute : EntityWithGuid
{
... Other mappings ....
[ForeignKey("Category_Id")]
public virtual Category Category { get; set; }
public string Category_Id { get; set; }
[ForeignKey("Attribute_Id")]
public virtual Attribute Attribute { get; set; }
public string Attribute_Id { get; set; }
}
If I run the command below, it works fine and the result SQL is
var query = Attribute.Where(x => !x.CategoryAttributes.Any());
SELECT
Extent1.Id,
Extent1.Name,
Extent1.Type,
Extent1.Active
FROM
Attribute AS Extent1
WHERE
NOT EXISTS( SELECT
1 AS C1
FROM
CategoryAttribute AS Extent2
WHERE
Extent1.Id = Extent2.Attribute_Id)
But if I put one more clause appears a Project2 alias for Attribute instead Extent1 and gives error because inside the exists clause within the remains Extent1.Id
var query = Attribute.Where(x => !x.CategoryAttributes.Any(y=>y.Category_Id == idcategory));
SELECT
Project2.Id,
Project2.Name,
Project2.Type,
Project2.Active
FROM
Attribute AS Project2
WHERE
NOT EXISTS( SELECT
1 AS C1
FROM
CategoryAttribute AS Extent2
WHERE
(Extent1.Id = Extent2.Attribute_Id)
AND (Extent2.Category_Id = #p__linq__0))
The exception is
Unknown column 'Extent1.Id' in 'where clause'

Answer 1

Found the problem.
After performing a simple query and receive an error similar thought something was wrong. Below the query, SQL and the undesirable alias Project
User.Where(x => x.Name.Contains(partialName))
SELECT
Project1.Id,
Project1.Name
FROM
User AS Project1
WHERE
(LOCATE('Marcelo', Extent1.Name)) > 0
ORDER BY Project1.Name ASC
Recently I upgraded MySql and with it came the new Net connector, version 6.7.4. I went back to the previous Net connector version (6.5.6) and everything is working again.