I see the problem seem you have problem when submit brand from before save, it will show error when the form submit are null (dont have any data in post request). Maybe the problem only in your site server. Please provide me the admin account and FTP account of your site. I wil try to check the problem in your site to give you correctly solution.
Answer for Hi, in ves extroic insertion of a new brand appears the error "Unable to find cat to save", what does it mean? How can I solve this?