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

Apple Logo Zoomed

Tim Cook Teases Plans for Apple's Upcoming 50th Anniversary

Thursday February 5, 2026 12:54 pm PST by
Apple turns 50 this year, and its CEO Tim Cook has promised to celebrate the milestone. The big day falls on April 1, 2026. "I've been unusually reflective lately about Apple because we have been working on what do we do to mark this moment," Cook told employees today, according to Bloomberg's Mark Gurman. "When you really stop and pause and think about the last 50 years, it makes your heart ...
wwdc sans text feature

Apple Rumored to Announce New Product on February 19

Thursday February 5, 2026 12:22 pm PST by
Apple plans to announce the iPhone 17e on Thursday, February 19, according to Macwelt, the German equivalent of Macworld. The report, citing industry sources, is available in English on Macworld. Apple announced the iPhone 16e on Wednesday, February 19 last year, so the iPhone 17e would be unveiled exactly one year later if this rumor is accurate. It is quite uncommon for Apple to unveil...
Finder Siri Feature

Why Apple's iOS 26.4 Siri Upgrade Will Be Bigger Than Originally Promised

Friday February 6, 2026 3:06 pm PST by
In the iOS 26.4 update that's coming this spring, Apple will introduce a new version of Siri that's going to overhaul how we interact with the personal assistant and what it's able to do. The iOS 26.4 version of Siri won't work like ChatGPT or Claude, but it will rely on large language models (LLMs) and has been updated from the ground up. Upgraded Architecture The next-generation...
iOS 26

iOS 26.3 and iOS 26.4 Will Add These New Features to Your iPhone

Tuesday February 3, 2026 7:47 am PST by
While the iOS 26.3 Release Candidate is now available ahead of a public release, the first iOS 26.4 beta is likely still at least a week away. Following beta testing, iOS 26.4 will likely be released to the general public in March or April. Below, we have recapped known or rumored iOS 26.3 and iOS 26.4 features so far. iOS 26.3 iPhone to Android Transfer Tool iOS 26.3 makes it easier...
maxresdefault

Apple Shows Off a Key Reason to Upgrade to the iPhone 17

Saturday February 7, 2026 9:26 am PST by
Apple today shared an ad that shows how the upgraded Center Stage front camera on the latest iPhones improves the process of taking a group selfie. "Watch how the new front facing camera on iPhone 17 Pro takes group selfies that automatically expand and rotate as more people come into frame," says Apple. While the ad is focused on the iPhone 17 Pro and iPhone 17 Pro Max, the regular iPhone...

Top Rated Comments

sniffies Avatar
176 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
176 months ago
"Apple seeds first seed..."

Stellar writing there. Well done MacRumors.
Score: 11 Votes (Like | Disagree)
Prodo123 Avatar
176 months ago
Hope this fixes the battery issue.
Score: 10 Votes (Like | Disagree)
thelink Avatar
176 months ago
Steve Jobs would never had allowed this. ;)
Score: 9 Votes (Like | Disagree)
Watabou Avatar
176 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
176 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)