macOS 10.13.4 High Sierra SDK Release Notes



macOS 10.13.4 SDK provides support for developing macOS apps. It’s packaged with a complete set of Xcode tools, compilers, and frameworks for creating apps for iOS, watchOS, tvOS, and macOS. These tools include the Xcode IDE and the Instruments analysis tool, among many others.

With this software you can develop apps for MacBook, MacBook Air, MacBook Pro, iMac, iMac Pro, Mac Pro, and Mac Mini running macOS High Sierra 10.13.4.

Tools and Developer Resources

You obtain Xcode 9.3 from the Mac App Store. It is a free download that installs directly into the Applications folder.

The Apple Developer Program provides everything you need to build and distribute your apps on the App Store for iPhone, iPad, Mac, and Apple Watch. Membership includes access to beta OS releases, advanced app capabilities, and tools to develop, test, and distribute apps and Safari extensions. For more information, visit Apple Developer Program.

Apple provides the following resources to support development in macOS:

Bug Reporting

For issues not mentioned in Notes and Known Issues, please file bugs through the Apple Developer website

When filing a bug, please include the full version number in the bug title and in the description. To find the version number, choose About this Mac from the Apple Menu, then click on the version number in the window that appears to show the full version number including the part in parenthesis. The full version number looks like 10.13.4 (17Exxx).

Additionally, you may discuss these issues and macOS 10.13.4 SDK in the Apple Developer Forums: To get more information about iCloud for Developers, go to

Release Notes Updates

macOS Release Notes is sometimes updated after a release is distributed. You can check for the most up-to-date version of macOS Release Notes at the Apple Developer website by checking

Revision: macOS10134 - MRN1

System Requirements

macOS 10.13.4 SDK supports the following Macs:

New 64-bit testing mode

Developers can use a new 64-bit testing mode in macOS 10.13.4 to test software for 64-bit compatibility.

To enable the 64-bit testing mode:

  1. Boot to Recovery OS by restarting your machine and holding down the Command and R keys at startup.

  2. Launch Terminal

  3. Execute the following command: nvram boot-args="-no32exec"

  4. Restart the machine

The 64-bit testing mode prevents 32-bit processes from launching. Launching an app that depends on 32-bit software results in a notification that the application can't be opened. Other types of software may fail silently, such as 32-bit versions of Dashboard and WebKit plugins, preference panes, and background processes.

Disable the test mode once the software is updated to work in 64-bit.

To disable the 64-bit testing mode:

  1. Boot to Recovery OS by restarting your machine and holding down the Command and R keys at startup.

  2. Launch Terminal

  3. Execute the following command: nvram boot-args=""

  4. Restart the machine

In future releases, the 64-bit testing mode may provide additional information for the developer to help test and qualify software.

Notes and Known Issues

The following items relate to using macOS SDK to develop code.


Resolved Issues

  • Fixed an issue that may result in system shutdown during installation of macOS 10.13.4. (36843839)

  • Dragging URLs from the address bar in Safari to Finder now works correctly. (36895105)

  • Fixed an issue that resulted in Safari stalling during video streaming. (37019360)

  • Fixed an issue with App Store and iBooks that resulted in a “Cannot Connect to the Store” error. (37033819)

  • Fixed an issue that resulted in the App Store not showing the password field during authentication. (37082239)

  • macOS Recovery over Wi-Fi is not supported on iMac Pros in macOS 10.13.4 beta 3. (37503394)

  • Setting the services order may not work in Network Preferences Pane. (35918049)

  • Cities added to Weather widget when not signed into iCloud may disappear. (36520283)

  • Mac App Store may exit unexpectedly after agreeing to updated Terms & Conditions. (35495094)

  • macOS 10.13.4 cannot be installed over macOS 10.13.3 Supplemental Update build 17D2104.

  • Safari may randomly crash. (36904314)

Known Issues

  • Portions of the display may flicker on some devices. (37003292)


Known Issues

  • Clients of NSURLSessionStreamTask that use a non-secure connection fail to connect when an error occurs during PAC file evaluation and the system is configured for either Web Proxy Auto Discovery (WPAD) or Proxy Automatic Configuration (PAC). A PAC evaluation failure can occur when the PAC file contains invalid JavaScript or the HTTP host serving the PAC file is unreachable. (33609198)

    Workaround: Use startSecureConnection() to establish a secure connection.


Known Issues

  • Messages may be unresponsive on launch.

  • All conversations may be missing.

  • Conversations may be slow to appear.