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"Failed to prepare the software update. Please try again."

Le0M

Le0M

macrumors 65816
Original poster
After macOS 27 download is complete, installation won't go through.

Here's my machine
MBP M1 2020 (regular).
Installed: macOS Tahoe 26.5.1
Space available on ssd: 70+ GB

Here's what I tried so far:
Restart the computer
Boot in Safe Mode and upgrade from there
Reset internet settings
Uninstalled VPN
Waited for 8 hours from macOS 27 release time

Still no luck.


Anyone else in my situation?
Any suggestions on how to proceed?
 
Le0M said:
After macOS 27 download is complete, installation won't go through.

Here's my machine
MBP M1 2020 (regular).
Installed: macOS Tahoe 26.5.1
Space available on ssd: 70+ GB

Here's what I tried so far:
Restart the computer
Boot in Safe Mode and upgrade from there
Reset internet settings
Uninstalled VPN
Waited for 8 hours from macOS 27 release time

Still no luck.


Anyone else in my situation?
Any suggestions on how to proceed?
Click to expand...
same here. M3Max MBP with 64GB RAM and about 400GB free SSD (out of 4TB). Odd. All macOS updates this year required safe mode - as it would go all the way to the end, with "5 min remaining" and then error. Safe mode not being enough today - will try psp123's suggestion but would have to check if it's set to Reduced Security or not in the first place.
 
psp123 said:
Try to boot into recovery mode and change "Reduced Security" to "Full Security" for Macintosh HD.
Click to expand...
Already switched to full security. Downloading OS right now. Let's see if it works this time 🤞🏻
 
Michaelhuisman said:
same here. M3Max MBP with 64GB RAM and about 400GB free SSD (out of 4TB). Odd. All macOS updates this year required safe mode - as it would go all the way to the end, with "5 min remaining" and then error. Safe mode not being enough today - will try psp123's suggestion but would have to check if it's set to Reduced Security or not in the first place.
Click to expand...
switching to Full Security worked. Now the question is why it was on "Reduced"? Some really small audio plugin developers don't notarize their plugins - maybe 5 or so that I use... but normally there's no way in heck that I'd reduce the standard security profile, so a bit surprised - will leave on Full and see what, if anything is broken. Hmmm...
 
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Michaelhuisman said:
switching to Full Security worked. Now the question is why it was on "Reduced"? Some really small audio plugin developers don't notarize their plugins - maybe 5 or so that I use... but normally there's no way in heck that I'd reduce the standard security profile, so a bit surprised - will leave on Full and see what, if anything is broken. Hmmm...
Click to expand...
Perhaps the reduced security is set by default.
 
M2 Ultra Mac Studio
Having the same problem installing.
Tried the "Full Security" trick but didn't work.
Kind of stuck about what to try next.

UPDATE: Now it has worked. Not sure what made it go through this time.
 
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I had to switch to Full Security e.g. enable SIP. But I had a bit of a brown trouser moment as my uninstall of Little Snitch didn't work the official way and the system extensions are still there. Right pain as they don't show in the UI as extensions. And as they were there they blocked all network traffic.

After macOS 27 with SIP I can no longer do a safe boot either. Damn my trousers were really getting to a state where I was like oops, why did I already upgrade.

And in recovery mode in the terminal or security utility can't disable SIP either. I was seriously getting worried but happy that the system works.

It also means you can't rename folders, delete it manually etc. So I was sweating it....


But then in Settings, Network, VPN/Proxies I noticed the little snitch Content filter and DNS filter. Disabled that and boom, it came alive.

I still can't remove it, and the extensions are still enabled but at least it is working again. Phew, I lost 4 hours this afternoon 🤣
 
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cyb3rdud3 said:
And in recovery mode in the terminal or security utility can't disable SIP either.
Click to expand...

So, after installing macOS 27, could you disable SIP again? I couldn't exactly understand it from your post, sorry.

I also get the same fake error message "Failed to prepare the software update." I don't intend to enable SIP so far, I need it off.

I call the message "fake" because it doesn't state the correct reason for installation failure. No should disabled SIP prevent the installation. So, basically it's a bug in the macOS 27 installer that Apple should fix. I submitted it as FB23208638 on June 16.
 
zevrix said:
So, after installing macOS 27, could you disable SIP again? I couldn't exactly understand it from your post, sorry.

I also get the same fake error message "Failed to prepare the software update." I don't intend to enable SIP so far, I need it off.

I call the message "fake" because it doesn't state the correct reason for installation failure. No should disabled SIP prevent the installation. So, basically it's a bug in the macOS 27 installer that Apple should fix. I submitted it as FB23208638 on June 16.
Click to expand...
No, can't disable it.
 
There's a bug in the first (current) release of GG that prevents the user from disabling both "Startup Security" and/or SIP.

Found this out after an AI-assisted search.

I will repost only a small portion of what the AI search said.
===
re the SIP bug:
"The Secure Enclave rejects the manifest hash of the Preboot volume, even if the volume itself is correct (e.g., showing the correct build number like 26A5353q).
This prevents any modification to the security policy, including disabling System Integrity Protection (SIP)."

re the Startup Security bug:
"In the Golden Gate beta, the Secure Enclave often becomes desynchronized with the Preboot volume after an upgrade.
Manifest Verification Failure: When you attempt to lower security via the Startup Security Utility or csrutil, the Secure Enclave rejects the request because the cryptographic manifest of the Preboot volume does not match its internal state."
===

This may get "fixed" (set back to the "way it used to be" at some future release. Perhaps even the public beta that is coming next month. We'll just have to wait and see.

UPDATE:
Beta 2 FIXES both these bugs.
It's now possible to select reduced startup security
and
It's also possible to disable System Integrity Protection.

If you have the beta running on an external SSD (as I do), be sure that you have that set as your startup disk.
Then... power down.
Then... press and hold the power on button, and get to the Options/recovery pane, and continue from there.
 
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