Surgical end effectors having an empty and missing cartridge lockout are disclosed. The surgical end effectors can comprise a first jaw, a second jaw rotatably coupled to the first jaw, and a multi-function firing member configured to translate during a firing stroke, wherein the firing member comprises a notch. The surgical end effectors can also include a lockout spring comprising a hook. The notch in the firing member can be aligned to receive the hook during the firing stroke unless an unfired staple cartridge is positioned in the first jaw. A sled assembly of the unfired staple cartridge can be positioned to deflect the hook out of alignment with the notch.
