Apple Seeds First Build of OS X 10.8.1 to Developers

Following on the heels of our report from Wednesday about Apple's preparations for developer seeds of OS X 10.8.1, Apple has now released the first build of the Mountain Lion update to developers, according to 9to5Mac.

The release has a build number of 12B13 and Apple reports no known issues, but asks developers to focus on a wide variety of areas for their testing. The delta update -- where only items that have changed are downloaded -- weighs in at 36.4MB.

NewImage
According to 9to5Mac, developers have been asked to test Active Directory, Microsoft Exchange in Mail, PAC proxies in Safari, SMB, USB, and Wi-Fi and audio when connected to the Apple Thunderbolt display.

The OS X 10.8.1 seed is available for download via the OS X Developer portal at developer.apple.com.

Popular Stories

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...
Sad Siri Feature

Apple AI Chief John Giannandrea Retiring After Siri Delays

Monday December 1, 2025 2:16 pm PST by
Apple AI chief John Giannandrea is stepping down from his position and retiring in spring 2026, Apple announced today. Giannandrea will serve as an advisor between now and 2026, with former Microsoft AI researcher Amar Subramanya set to take over as vice president of AI. Subramanya will report to Apple engineering chief Craig Federighi, and will lead Apple Foundation Models, ML research, and ...
Netflix Smaller 4

Netflix Kills Casting From Its Mobile App to Most Modern TVs

Monday December 1, 2025 4:36 am PST by
Netflix has quietly removed the ability to cast content from its mobile apps to most modern TVs and streaming devices, including newer Chromecast models and the Google TV Streamer. The change was first spotted by users on Reddit and confirmed in an updated Netflix support page (via Android Authority), which now states that the streaming service no longer supports casting from mobile devices...
Cyber Week Deals 2025

Best Cyber Week Apple Deals Include Big Discounts on AirPods, Apple Watch, and More

Sunday November 30, 2025 7:33 am PST by
Cyber Week is here, and you can find popular Apple products like AirPods, iPad, Apple Watch, and more at all-time low prices. In this article, the majority of the discounts will be found on Amazon. Note: MacRumors is an affiliate partner with some of these vendors. When you click a link and make a purchase, we may receive a small payment, which helps us keep the site running. Specifically,...
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 ...
Touchscreen MacBook Feature

Here Are the Four MacBooks Apple Is Expected to Launch Next Year

Monday December 1, 2025 5:00 am PST by
2026 could be a bumper year for Apple's Mac lineup, with the company expected to announce as many as four separate MacBook launches. Rumors suggest Apple will court both ends of the consumer spectrum, with more affordable options for students and feature-rich premium lines for users that seek the highest specifications from a laptop. Below is a breakdown of what we're expecting over the next ...
studio display purple february

M5 iPad Pro Could Hint at New Studio Display Feature

Sunday November 30, 2025 10:30 am PST by
The updated specs of the M5 iPad Pro may point toward a major new feature for Apple's next-generation Studio Display expected in early 2026. Apple's latest iPad Pro debuted last month and contains one display-related change that stands out: it can now drive external monitors at up to 120Hz with Adaptive Sync. The feature should deliver lower latency, smoother motion, and fewer visual...
iPhone Pocket Short

iPhone Pocket is Now Completely Sold Out Worldwide

Tuesday November 25, 2025 7:16 am PST by
Apple recently teamed up with Japanese fashion brand ISSEY MIYAKE to create the iPhone Pocket, a limited-edition knitted accessory designed to carry an iPhone. However, it is now completely sold out in all countries where it was released. iPhone Pocket became available to order on Apple's online store starting Friday, November 14, in the United States, France, China, Italy, Japan, Singapore, ...
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...
iOS 26

What to Expect From Apple This December: iOS 26.3 Beta, Replay 2025, and More

Monday December 1, 2025 8:40 am PST by
The calendar has turned to December, and the quieter year-end holiday season is now upon us. Nevertheless, we can still expect a few things from Apple this month. Apple previously announced that iOS 26.2 will be released to the general public in December, and we can expect corresponding updates to be released as well, including iPadOS 26.2, macOS 26.2, watchOS 26.2, tvOS 26.2, and visionOS...

Top Rated Comments

sniffies Avatar
174 months ago
Hope this release fixes the bug where folder item count wouldn't update no matter what.

Score: 36 Votes (Like | Disagree)
tekno Avatar
174 months ago
"Apple seeds first seed..."

Stellar writing there. Well done MacRumors.
Score: 11 Votes (Like | Disagree)
Prodo123 Avatar
174 months ago
Hope this fixes the battery issue.
Score: 10 Votes (Like | Disagree)
thelink Avatar
174 months ago
Steve Jobs would never had allowed this. ;)
Score: 9 Votes (Like | Disagree)
Watabou Avatar
174 months ago
Rather small update....
It's actually a fairly big update. Code files are typically only a couple of kilobytes in size. So a 36.4MB update is fairly big. And anyways, Apple probably wants to just focus on the most critical updates first and then move on to the graphical bugs. Plus, this is only the first build.
Score: 6 Votes (Like | Disagree)
cjmillsnun Avatar
174 months ago
In other words, the biggest train wreck in OS X's history continues to be a train wreck with 10.8.1...other than the battery, nothing else is fixed or what?

Considering you've never bought ML and used it on your own mac. I don't think you're in a position to call it "The biggest train wreck in OS X's history". I've been using it since DP1 on my own Macs and it has held up fairly well.

There were far worse bugs in 10.6 when that came out but at the time you were saying "Microsoft is dead".

On the whole, the bugs in ML are relatively minor for a .0 release, and some of them are being fixed in this .1 release. This .1 developer release is the first seed. So again there may be more in the way of bug fixes to come in the next seed.

Your post is quite frankly ridiculous.
Score: 5 Votes (Like | Disagree)