Just after its opening keynote this afternoon, Apple released OS X Mountain Lion Developer Preview 4 (build 12A239) and Server Preview 5 (build 12S254j) to developers. Unlike previous developer previews of Mountain Lion, Apple does not ask developers to look into any certain issues, perhaps because Mountain Lion is going to ship in July for $19.99 (a GM to come soon?). Apple also does not list any issues out of the ordinary, as you can see in the release note after the break.

For those looking to test the new Facebook integration announced today (much like Twitter) within Mountain Lion, you could download a separate .dmg from the Developer Center titled “OS X Facebook Developer Preview.” If you are registered with Apple’s paid developer program, you can get the Mountain Lion update on the Developer Center now. For those who are not, it does not look like you will be waiting much longer to play with this latest beast. Let us know if you find anything: tips@9to5mac.com.

OS X Mountain Lion Developer Preview 4 Seed Note

OS X Mountain Lion Developer Preview 4 is prerelease software. Do not use this prerelease software in a commercial operating environment or with important data. You should back up all of your data before installing this software and regularly back up data while using the software. You will not be able to upgrade from the OS X Mountain Lion Developer Preview to the final release.

If an installation of OS X Developer Preview 4 fails, try using Disk Utility from a Recovery HD to repair the disk.

Architecture Requirements

The OS X Mountain Lion Developer Preview supports the following Macs:

  • • iMac (Mid 2007 or newer)
  • • MacBook (Late 2008 Aluminum, or Early 2009 or newer)
  • • MacBook Pro (Mid/Late 2007 or newer)
  • • MacBook Air (Late 2008 or newer)
  • • Mac mini (Early 2009 or newer)
  • • Mac Pro (Early 2008 or newer)
  • • Xserve (Early 2009)

Known Issues

  • Network Migration requires OS X 10.7.3 or later in this Developer Preview

⁃ International users may be unable to enter a Wi-Fi password while in Setup Assistant.  Users can select Other Network Options and continue setting up their system without a Wi-Fi network

  • On systems with FileVault enabled, the login window may be displayed incorrectly
  • Rotating an external display may cause a panic on AMD Radeon-based machines
  • QuickTime screen recordings may produce corrupted videos or cause an exception when run on machines with NVDIA graphics
  • Installation of Final Cut Studio 3 may cause a hang unless Automatic Graphics Switching is disabled in Energy Saver Preferences

Game Center

  • In this seed, the Game Center application will view Production data by default. Games in development will be programmatically switched to use the Sandbox server environment
  • No Top Games are displayed on the Me tab and no game recommendations are shown on the Games tab
  • To use Game Center in your game on OS X, you must install a provisioning profile that enables Game Center for your app.  Code signing, entitlements, and provisioning profiles are all described in detail in Tools Workflow Guide for Mac
  • Tell-a-Friend functionality is not available
  • The local peer-to-peer GameKit API (GKSession, GKPeerPickerController, and related classes) is not supported

Bug Reporting 

This build is being provided to you for testing and development purposes. Should you encounter any problems, please submit a bug report using the online Bug Reporter at <http://bugreporter.apple.com/>. Please make sure to include “10.8 (12A239)” in the bug title and description. This information will ensure that your bug is processed quickly.

When submitting a bug report, please make sure to include a Summary, Steps to Reproduce, Expected Results, Actual Results, and the diagnostic output generated by running ‘sudo sysdiagnose’ in the Terminal.

For complete instructions on submitting bug reports, please visit the Bug Reporting page at <http://developer.apple.com/bugreporter/>.

Thank you for your support.

Worldwide Developer Relations

Apple Inc.