Download OS X Mountain Lion 10.8.5 Build 12F36 – Developer News

Apple hands testers the ninth beta of OS X 10.8.5 ahead of Mavericks release

As of yesterday, a new beta of OS X Mountain Lion is available for testing. OS X Mountain Lion 10.8.5 build 12F36 is the ninth beta in this particular development cycle and arrives weeks (or perhaps only days) before the launch of OS X 10.9 Mavericks.

Apple says OS X Mountain Lion 10.8.5 Build 12F36 has no known issues, but the Cupertino giant still requires testers to look over key areas of the operating system searching for (and reporting) bugs.

These focus areas include Wi-Fi, Graphics, Wake from Sleep, PDF viewing and Accessibility, and Mobile Device Management.

The barebones delta update weighs in at close to 300MB, whereas the Combo installer is a hefty 850MB download.

Apple asks developers who are installing Mountain Lion for the first time to ensure they have a 64-bit Intel Mac that’s running Mac OS X v10.6.7 Snow Leopard or OS X Lion, as well as 8GB of free space. For development purposes, Xcode 4.4 is required.

Testers must also be aware that they will not be able to revert to a previous system state after updating to the new OS X Mountain Lion 10.8.5 Build 12F36.

As such, anyone taking a chance on this build must do so on a system they are prepared to erase if necessary, Apple says.

Developers who encounter any problems are urged to submit a bug report using the online Bug Reporter (located at using “10.8.5 (12F36)” in the bug title and description, for good reference.

According to people who are familiar with the seed notes, Apple says bug reporting must include “a Summary, Steps to Reproduce, Expected Results, Actual Results, and the diagnostic output generated by running ‘sudo sysdiagnose’ in the Terminal.”

To download the new Mountain Lion beta, visit Apple’s Mac Dev Center with your developer credentials in hand.

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