There is an attribute that dont exist after upgrading from 9.6.8 to 9.15.1, and somehow I can't edit domain model. It says "This domain model is read only; you can use its entities and attributes when creating yor app".
Gil Laurence Aranco
I believe you are trying to work with the system module and yes it is read only. You will have to change your display or entities attached to it to take in to account the changes that have taken place.