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by vcanales 2045 days ago
I tried upgrading a 2019 iMac with Catalina to BigSur. It failed after the black screen with the apple logo and a count down, by going to a screen I've never seen before that said something like "failed to _apply_ update". If I restarted, then I would land on the same countdown screen until it inevitably failed again.

I ended up deleting the hard drive and reinstalling Catalina, but the weird thing is that now my 2019 iMac with Catalina plays the boot chime, which is the only part of Big Sur that worked for me...
1 comments
Tsiklon 2045 days ago
The machine always could, for newer machines they decided to mute it for some reason, there's an NVRAM setting, if you want to mute the chime again: `sudo nvram StartupMute=%01`

and the reverse: `sudo nvram StartupMute=%00`

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userbinator 2045 days ago
That's just Apple deciding for the users, like it has always been doing. It's funny to see the setting for it is so hidden; my PC motherboard has a "POST beep" setting in the BIOS setup, which doesn't require a terminal in a working OS to get to, and whose presence is helpfully reminded each time I turn it on ("press DEL to enter SETUP").
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Tsiklon 2044 days ago
It doesn't necessarily require a working OS - you can of course use either of the two recovery systems (On Disk, or Internet Recovery), a bootable time machine drive(IIRC) or an OS X installation USB Drive to do so.

I do agree however that the low level system tunables are unfortunately very hidden.

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saagarjha 2045 days ago
On new hardware, this setting has been moved to System Preferences.
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