I enter rails_admin and it works normally with users, but when I edit an activity it gives this error.
I've already researched what it can be, but I did not find anything very clear. So I'm going to put my activity model to help with the understanding, and anything is just to warn that I edit or share some specific files for better understanding.
MODEL
class Activity < ApplicationRecord
belongs_to :user
before_update :impedir_duplicata
after_update :validar_hora
after_update :deletar_anexo
before_destroy :retirar_hora
before_destroy :deletar_anexo
mount_uploaders :documents, DocumentUploader
validates :hora_computada, :titulo, :grupo, :data_evento,
:local_realizacao_atividade, :relatorio, presence: true