32-bit applications will no longer be supported
Since this 64-bit test mode will prevent 32-bit processes from running on the system, Apple recommends turning off this feature with the sudo nvram boot-args = '' command on the Terminal and then restarting the computer. when you have updated your application.
Apple also said 64-bit testing features will be improved in the future for developers to check and update the application to meet new requirements. When macOS 10.14 is released (will be revealed this summer at WWDC 2018), 32-bit support will be completely removed.
macOS High Sierra currently supports the following lines:
This is the link to download macOS High Sierra 10.13.4 from the Apple Developer site.
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