If you can upload your project here, I can take a quick look and let you know what's wrong.

The EntityManager is not thread-safe. See http://drc.ideablade.com/xwiki/bin/view/Documentation/entitymanager-not-thread-safe.

What most likely happen is that the EM is created on another thread but is executing query on a different thread.

I get this error and i don't know how to solve it. The error is thrown on this method:

public static List<TIPI_RECAPITI> GetTipiRecapiti()

        {

            var query = from q in dbContext.TIPI_RECAPITI

                        orderby q.ID ascending

                        select q;

            return query.ToList<TIPI_RECAPITI>();

        }