Russ Hughes of Studio-One-Expert posted an extensive list of links to many of the manufacturers concerning Apple's latest OS X update "El Capitan". Universal audio is not mentioned so I went to their site. The initial tests suggest that the firewire Apollos and Satellites are not compatible but the Thunderbolt units seem to be compatible. UA does not recommend updating to "El Capitan" at this time. You can check the entire list here.