Apple has seeded a new beta of OS X 10.8.1 to developers, exactly a week after the first build came out, according to 9to5Mac.

The release has a build number of 12B17 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 43.27MB.

Mountainlionbeta
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 same list of items as the prior release.

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

Top Rated Comments

milo Avatar
176 months ago
No, I haven't installed it - but I have been following the various reports of hard crashes, absurdly short battery life and iOS-like oddities. And it doesn't seem that great to me.

So whining about something you've never even tried. Thanks, that's useful.

There are always problems with any release of any software, OS or otherwise, so anyone could declare any release a "train wreck" if the only basis for that is some people reporting problems online.

What really matters is how widespread problems are and how severe they are. Problems are to be expected for any .0 release, and for a .0 release it's surprisingly solid (heck of a lot better than 10.7.0, and I suspect better than 10.7.4 for most people).

It's just common knowledge, anyone doing mission critical work or otherwise sensitive to issues should skip all .0 releases (and often one or two after that). And those that do need not regale us with whining about problems they've just heard about, that adds nothing to the discussion.
Score: 9 Votes (Like | Disagree)
Ulf1103 Avatar
176 months ago
Possible release next week since there are no known issues.

All things considered Mountain Lion has been pretty much problem free for a 10.x.0 release.

Then please, read every post in this thread:

https://discussions.apple.com/thread/4135250?start=0&tstart=0

and then report back :P
Score: 8 Votes (Like | Disagree)
Cynicalone Avatar
176 months ago
Possible release next week since there are no known issues.

All things considered Mountain Lion has been pretty much problem free for a 10.x.0 release.
Score: 7 Votes (Like | Disagree)
mw360 Avatar
176 months ago
So, still no fix for the "weighs in at" issue. :rolleyes:
Score: 6 Votes (Like | Disagree)
Kariya Avatar
176 months ago
Install the OS and see for yourself if it really is that terrible instead of complaining for the sake of complaining.

As it stands you're just whining and whining...and its quite annoying to read in every other thread one comes across.
Score: 4 Votes (Like | Disagree)
9982225 Avatar
176 months ago
And people CONTINUE to spout the same nonsense about the purported advantages of a "clean install" - for every five positive reports, I can show you five OTHER reports in these forums from users who have the same if not worse problems AFTER a clean install.

So let's stop with this placebo recipe, shall we?[COLOR="#808080"]

I did a clean install. It worked for ME, perhaps it will not work for YOU or OTHER people but it worked for ME. A clean install of a new OS is never a bad thing to get rid of left over files here and there.

It's not the end all be all solution to anything, but it can be beneficial. I know you do not think so but so far as I can tell you don't like much of anything.
Score: 4 Votes (Like | Disagree)

Popular Stories

Aston Martin CarPlay Ultra Screen

Apple's CarPlay Ultra to Expand to These Vehicle Brands Later This Year

Sunday February 1, 2026 10:08 am PST by
Last year, Apple launched CarPlay Ultra, the long-awaited next-generation version of its CarPlay software system for vehicles. Nearly nine months later, CarPlay Ultra is still limited to Aston Martin's latest luxury vehicles, but that should change fairly soon. In May 2025, Apple said many other vehicle brands planned to offer CarPlay Ultra, including Hyundai, Kia, and Genesis. In his Powe...
Apple Logo Black

Apple's Next Launch is 'Imminent'

Sunday February 1, 2026 12:31 pm PST by
The calendar has turned to February, and a new report indicates that Apple's next product launch is "imminent," in the form of new MacBook Pro models. "All signs point to an imminent launch of next-generation MacBook Pros that retain the current form factor but deliver faster chips," Bloomberg's Mark Gurman said on Sunday. "I'm told the new models — code-named J714 and J716 — are slated...
Apple MacBook Pro M4 hero

New MacBook Pros Reportedly Launching Alongside macOS 26.3

Sunday February 1, 2026 5:42 am PST by
Apple is planning to launch new MacBook Pro models with M5 Pro and M5 Max chips alongside macOS 26.3, according to Bloomberg's Mark Gurman. "Apple's faster MacBook Pros are planned for the macOS 26.3 release cycle," wrote Gurman, in his Power On newsletter today. "I'm told the new models — code-named J714 and J716 — are slated for the macOS 26.3 software cycle, which runs from...
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
We are still waiting for the iOS 26.3 Release Candidate to come out, so the first iOS 26.4 beta is likely still at least a week or two 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...
14 inch MacBook Pro Keyboard

Apple Changes How You Order a Mac

Saturday January 31, 2026 10:51 am PST by
Apple recently updated its online store with a new ordering process for Macs, including the MacBook Air, MacBook Pro, iMac, Mac mini, Mac Studio, and Mac Pro. There used to be a handful of standard configurations available for each Mac, but now you must configure a Mac entirely from scratch on a feature-by-feature basis. In other words, ordering a new Mac now works much like ordering an...