Usually called "the release the shutter the lens is not installed", you can modify the settings to allow. Specifically refer to the camera manual.

Although the lens will fit physically, automatic diaphragm, auto-focusing, or any other functions will not operate while using this adapter. There is no electrical contacts in the adapter ring. Full manual operation, manual focus, manual iris adjustment can be achieved with body manual exposure, aperture priority exposure.In this case "stop-down mode" will need to be used when metering since the lens does not have the ability to have its aperture controlled by the camera body. You can shoot in Manual or Aperture Priority Mode. Before use, set your camera Menu: "Shoot without lens".