ContraintViolation after upgrade Symfony from 4.2 to 4.3

Question

I'm using a2lix_translation with KnpDoctrineExtension.
I have a problem when create or update a record. Before upgrade Symfony to 4.3 works perfectly.

Now I've got this error ConstraintViolation:

Path: data.defaultLocale Message: "This value should be of type. App\Entity\Returns Invalid value "en" Thanks for your help. Sorry for my English.