We have same error with Seam 1.2.1-GA and JBoss 4.0.5-GA. Our problem was double assignment in @OneToOne relationship. | A a = new A(); | B b = new B(); | a.setB(b); | b.setA(a); | Solution: set the the relationship only to the object that own the mapping (table with foreign key) | A a = new A(); // if A has mapping | B b = new B(); | a.setB(b); | // b.setA(a); | View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4069000#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...