I tried to upgrade my MacBook Pro to the Developer Preview of OS X Yosemite (10.10); it went reasonably well until the second reboot. At this point it was sat there with a half-full progress bar under the Apple logo. I left it a few hours, nothing changed, so I set about fixing it.
A reboot holding-down the command-v combination revealed that the last thing on the screen was an error report about a bad shared library within the Accelerate framework.
Luckily I know what that means, so I made a Yosemite installer USB key, rebooted with that and used the terminal to copy the installer’s version of Accelerate.framework to the correct location in the installed system. This allowed my system to boot, but a few visuals were not working correctly.
At this point I didn’t know whether these are problems everyone has with Yosemite or problems with my ‘fix’. I logged in, and tried to launch Excel, which crashed. The crash report said that some part of the Accelerate framework did not have the correct architecture. Excel is a 32-bit program, and I suspect that the version in the installer image is 64-bit only (I didn’t bother to check).
I decided instead to try and copy the Accelerate.framework from another Mac running Mavericks (10.9). I couldn’t do this initially because none of my accounts had administrative rights. I managed to subvert OS X security to regain admin access, copied the framework and rebooted full of optimism. Sadly this just caused the return of my boot hang.
Final plan was to format the HD and install Yosemite clean from the USB key I made for recovery. This booted and had none of the glitches I had previously seen. I logged in with a new admin account, recreated my other accounts (the home directories are on another drive so I lost no data), and spent the following hour or so downloading and installing all the applications I lost.
So I’m back in business and lost nothing of lasting import (a day out of my week’s holiday, but the weather wasn’t great today anyway). But what happened? I don’t exactly know. I thought that the problem would be that Accelerate.framework had not been updated between Mavericks and Yosemite and the version on my Mac had suffered from bit rot. But this should not be the case as the version on my Mavericks mac is 1.9 and the new Yosemite install has 1.10 (with a significantly newer Source Version as well).
It’s odd, but since everything is now working I’m not inclined to worry overmuch about it.