Apple today seeded build 12F20 of OS X 10.8.5 to developers, offering a fourth 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 12F17.

Mountainlion12f20
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 three developer previews of OS X Mavericks and has announced that it will launch the new operating system to the public this fall.

Update: One tipster says the update fixed the Adobe Photoshop flickering issue that was reported last last month.

Top Rated Comments

gnurf Avatar
139 months ago
A pretty irrelevant post considering this a about Mavericks, not iOS.

Except it isn't about Mavericks :)
Score: 7 Votes (Like | Disagree)
HolgerR Avatar
139 months ago
A pretty irrelevant post considering this a about Mavericks, not iOS.

No. It's not.
Score: 3 Votes (Like | Disagree)
ValSalva Avatar
139 months ago
Will there be a 10.8.6?

Yays? Nays?

I think yes. 10.8.5 will be out well before Mavericks. Then work on 10.8.6 will begin. I highly doubt there will be any 10.8.7 though.
Score: 2 Votes (Like | Disagree)
cbs20 Avatar
139 months ago
Have any of you guys any experience in how things are running with the latest 10.8.5 vs the 10.9 dev ?

I had the first 10.9 dev build installed and it runs like a dream, but things like some adobe apps breaks, but I would hate going back to 10.8 (standard) because that was dreadful too... so currently i am running windows8.1 but would prefer to get back on a speedy osx :)

So if any of you for some reason have had too much time and have a feeling of both, let me know! thanks :P

First thing you have to consider is 10.8 is a much more established OS and 10.9 is only in beta. When DP1 for 10.9 was released that was the first time anybody at Adobe could get their hands on the OS and start optimizing applications to run in 10.9. On top of that the OS is constantly changing until its final release and applications may need to be tweaked with these changes to make sure they work with the OS. You can't make a good comparison of a beta OS to an established OS. Wait until 10.9 is released and app developers release their updates and then you can judge what OS to use.
Score: 1 Votes (Like | Disagree)
Mr. Wonderful Avatar
139 months ago
^As much as I hate waiting longer for new releases, I think year and a half OS X development cycles might be a good thing for everyone. It's more time to add more significant features, and it allows more time for the current OS to become rock solid, which is great for casual users and enterprise. I know I felt like Lion never got truly stable.
Score: 1 Votes (Like | Disagree)
Garrod Avatar
139 months ago
They should do weekly iOS 7 beta seeds too.

A pretty irrelevant post considering this a about Mavericks, not iOS.
Score: 1 Votes (Like | Disagree)

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