Thank you for your reponse.
Regarding what I read on internet about this kind of error, the solution is globally to set the fetch strategie to EAGER, witch in my case don’t solve the problème.
I can give more informations but the error don’t occured in my own code.
It occurred durring the PROCESS_VALIDATIONS phase of JSF. During this phase, JSF convert and validate the posted value, and then, put the SubmittedValue in the field Value of the UIComponent.
The content of the Value field come from the entityBean used to displayed the contenent ot the UIComponent, but should be detached since the previous transaction was closed. This is managed by the EE container who should close the EntityManager between each web request.
I don’t undestand why the exception is thrown. Is it because there is not opened transaction? In what kind of situation a collection is not initialized? In this case, I suppose the collection was initialized during the first request, while fetching the persistedBean and it’s collection.
Did this help ?