Walid,
The error message about the missing constructor is missleading here. What's actually going on is that the EntityManager fails to instantiate. I can tell that from the following error:
Unable to get metadata for xxx.Commun.Domain.Entities.News. Make sure it is a valid entity type or POCO type with a KeyAttribute
What does the inner exception say?
I see these errors primarly if PostSharp didn't do it's job, but maybe in this case it has something to do with the xap loading. I did test xap loading, but I don't remember if I tested it with a CF domain model in the dynamic xap. I have to put together a small repro and see If I get any issues.
Sorry, you are having these issues. We appreciate you attempting this migration. With a beta product there are bound to be issues.