Apple today seeded build 12F17 of OS X 10.8.5 to developers, offering a third version of the next Mac operating system update for testing. The release comes one week after the appearance of the previous beta of OS X 10.8.5, build 12F13.

12f17
As with previous betas, the update comes with no known issues and can be downloaded via Apple's Developer Page or through the software update tool in the Mac App Store.

Testing on OS X 10.8.5 comes as Apple is also continuing work on its next major version of OS X, Mavericks. Apple has already seeded two developer previews of OS X Mavericks and has announced that it will launch the new operating system to the public this fall.

Top Rated Comments

WildCowboy Avatar
162 months ago
Can any one explain to me why they are still doing this instead of putting extra work in Mavericks? Not that it bothers me, just asking

Mavericks isn't coming for months, and there are things in Mountain Lion that need fixing.
Score: 14 Votes (Like | Disagree)
beelzebubba Avatar
162 months ago
Can any one explain to me why they are still doing this instead of putting extra work in Mavericks? Not that it bothers me, just asking

Because many people still run ML and will even after Mavericks comes out. ML will likely be the end of the line for some older Macs and Apple has done fairly well in supporting legacy machines even past the five year end of life.
Score: 8 Votes (Like | Disagree)
laflores Avatar
162 months ago
Can any one explain to me why they are still doing this instead of putting extra work in Mavericks? Not that it bothers me, just asking

Because otherwise, people would start crying because "apple doesn't care about mountain lion any more" and some people will complain that mavericks is a piece of **** and they rather stay with snow leopard...
Score: 8 Votes (Like | Disagree)
rdlink Avatar
162 months ago
Gonna miss those cats when they're gone.
Score: 7 Votes (Like | Disagree)
iBug2 Avatar
162 months ago
(not trolling)

first time that safari has ever been snappier for me....running rMBP.....but it might also just be because safari in mavs is horrible

Are you kidding me? Safari 7.0 finally solves the memory issue which was introduced in 5.1 where when you open many tabs, web process just crashes. 7.0 does not have that, the single most annoying Safari bug in 2 years being solved finally.
Score: 5 Votes (Like | Disagree)
darkknight14 Avatar
162 months ago
Gonna miss those cats when they're gone.

Me too, every time I look at that new wave background it makes me want to go for a p***
Score: 4 Votes (Like | Disagree)

Popular Stories

iOS 26

15 New Things Your iPhone Can Do in iOS 26.2

Friday December 5, 2025 9:40 am PST by
Apple is about to release iOS 26.2, the second major point update for iPhones since iOS 26 was rolled out in September, and there are at least 15 notable changes and improvements worth checking out. We've rounded them up below. Apple is expected to roll out iOS 26.2 to compatible devices sometime between December 8 and December 16. When the update drops, you can check Apple's servers for the ...
iOS 26

Apple Seeds iOS 26.2 and iPadOS 26.2 Release Candidates to Developers and Public Beta Testers

Wednesday December 3, 2025 10:33 am PST by
Apple today seeded the release candidate versions of upcoming iOS 26.2 and iPadOS 26.2 updates to developers and public beta testers, with the software coming two weeks after Apple seeded the third betas. The release candidates represent the final versions of iOS 26.2 and iPadOS 26.2 that will be provided to the public if no further bugs are found during this final week of testing....
ios 18 to ios 26 upgrade

Apple Pushes iPhone Users Still on iOS 18 to Upgrade to iOS 26

Tuesday December 2, 2025 11:09 am PST by
Apple is encouraging iPhone users who are still running iOS 18 to upgrade to iOS 26 by making the iOS 26 software upgrade option more prominent. Since iOS 26 launched in September, it has been displayed as an optional upgrade at the bottom of the Software Update interface in the Settings app. iOS 18 has been the default operating system option, and users running iOS 18 have seen iOS 18...
Photos App Icon Liquid Glass

John Gruber Shares Scathing Commentary About Apple's Departing Software Design Chief

Thursday December 4, 2025 9:30 am PST by
In a statement shared with Bloomberg on Wednesday, Apple confirmed that its software design chief Alan Dye will be leaving. Apple said Dye will be succeeded by Stephen Lemay, who has been a software designer at the company since 1999. Meta CEO Mark Zuckerberg announced that Dye will lead a new creative studio within the company's AR/VR division Reality Labs. On his blog Daring Fireball,...
iOS 26

When Will Apple Release iOS 26.2?

Monday December 1, 2025 4:37 pm PST by
We're getting closer to the launch of the final major iOS update of the year, with Apple set to release iOS 26.2 in December. We've had three betas so far and are expecting a fourth beta or a release candidate this week, so a launch could follow as soon as next week. Past Launch Dates Apple's past iOS x.2 updates from the last few years have all happened right around the middle of the...
maxresdefault

iPhone Fold: Launch, Pricing, and What to Expect From Apple's Foldable

Monday December 1, 2025 3:00 am PST by
Apple is expected to launch a new foldable iPhone next year, based on multiple rumors and credible sources. The long-awaited device has been rumored for years now, but signs increasingly suggest that 2026 could indeed be the year that Apple releases its first foldable device. Subscribe to the MacRumors YouTube channel for more videos. Below, we've collated an updated set of key details that ...
iphone air camera

iPhone Air's Resale Value Has Dropped Dramatically, Data Shows

Thursday December 4, 2025 5:27 am PST by
The iPhone Air has recorded the steepest early resale value drop of any iPhone model in years, with new data showing that several configurations have lost almost 50% of their value within ten weeks of launch. According to a ten-week analysis published by SellCell, Apple's latest lineup is showing a pronounced split in resale performance between the iPhone 17 models and the iPhone Air....
ive and altman

Jony Ive's OpenAI Device Barred From Using 'io' Name

Friday December 5, 2025 6:22 am PST by
A U.S. appeals court has upheld a temporary restraining order that prevents OpenAI and Jony Ive's new hardware venture from using the name "io" for products similar to those planned by AI audio startup iyO, Bloomberg Law reports. iyO sued OpenAI earlier this year after the latter announced its partnership with Ive's new firm, arguing that OpenAI's planned "io" branding was too close to its...
iPhone 17 Pro Cosmic Orange

iPhone 17 Pro Lost a Camera Feature Pro Models Have Had Since 2020

Thursday December 4, 2025 5:18 am PST by
iPhone 17 Pro models, it turns out, can't take photos in Night mode when Portrait mode is selected in the Camera app – a capability that's been available on Apple's Pro devices since the iPhone 12 Pro in 2020. If you're an iPhone 17 Pro or iPhone 17 Pro Max owner, try it for yourself: Open the Camera app with Photo selected in the carousel, then cover the rear lenses with your hand to...
Intel Inside iPhone Feature

Apple's Return to Intel Rumored to Extend to iPhone

Friday December 5, 2025 10:08 am PST by
Intel is expected to begin supplying some Mac and iPad chips in a few years, and the latest rumor claims the partnership might extend to the iPhone. In a research note with investment firm GF Securities this week, obtained by MacRumors, analyst Jeff Pu said he and his colleagues "now expect" Intel to reach a supply deal with Apple for at least some non-pro iPhone chips starting in 2028....