Sony has released Mac OS X Driver Loader to enable firmware update compatibility with Mac OS 10.13 High Sierra. Mac 10.13 users must run this driver loader BEFORE connecting your camera.
Please Note: Mac OS 10.13 users must run “DriverLoader_1013” prior to ALL firmware updates.
Mac OS Security Settings must be set to:
System Preferences > Security & Privacy > Allow apps downloaded from: App Store and identified developers