Start64!Apple released earlier the first beta update of the upcoming macOS High Sierra 10.13.4 software update, which implements a new 64-bit testing mode to prepare users for deprecation of macOS 32-bit support.

Last year, Apple said that macOS High Sierra would be last macOS release to fully support 32-bit apps, and it looks like today's macOS High Sierra 10.13.4 beta update includes a new function that alerts users when they attempt to use a 32-bit app or an app that requires 32-bit software to be installed on the system.