Other than that, what else happens? Do you get redirected to profil_entite? Or do you remain on the current page? (This indicates whether the form submission passed the is_valid test.
Note: I see where you’re changing the ticket.statut field, but you’re not saving that instance of ticket, which means that field isn’t going to get updated in the database.
Also note: Setting the readOnly attribute in JavaScript does not prevent a user from altering the values in those fields. If you want those values to be unalterable, you must set the disabled (or readonly) attribute on those fields in the form.