"Failed to prepare the software update" when trying to update from Sonoma 14.4.1 to 14.5

[vinarski6k]

Hi all,
I'm trying to update my Intel iMac Retina 5K, 27-inch, 2020 from Sonoma 14.4.1 to 14.5 but keep getting a "Failed to prepare the software update" error. Here’s what I’ve tried so far:
1. Shutdown / restart the Mac
2. Boot into safe mode and then try to update
3. Disk check using "First Aid"
4. Manually update using Terminal:

sudo softwareupdate -i -a
This results in:

Software Update Tool

Finding available software
Downloading macOS Sonoma 14.5
Downloading: 100.00%
Failed to download & prepare update: Error Domain=SUOSUErrorDomain Code=201 "Failed to prepare the software update. Please try again." UserInfo={NSLocalizedRecoverySuggestion=An error occurred while downloading the selected updates. Please check your internet connection and try again., NSLocalizedDescription=Failed to prepare the software update. Please try again., NSUnderlyingError=0x600003f50000 {Error Domain=SUMacControllerError Code=7740 "[SUMacControllerErrorPrepareFailed=7740] Failed to perform Prepare operation: [MobileSoftwareUpdateErrorDomain(MSU):MSU_ERR_BRIDGEOS_PREPARE_FAILURE(45)_1_BOSErrorDomain:205_2_BridgeOSSoftwareUpdateError:19]" UserInfo={NSLocalizedDescription=Failed to prepare the software update. Please try again., SUMacControllerErrorIndicationsMask=0, NSDebugDescription=[SUMacControllerErrorPrepareFailed=7740] Failed to perform Prepare operation: [MobileSoftwareUpdateErrorDomain(MSU):MSU_ERR_BRIDGEOS_PREPARE_FAILURE(45)_1_BOSErrorDomain:205_2_BridgeOSSoftwareUpdateError:19], NSUnderlyingError=0x600003f52370 {Error Domain=MobileSoftwareUpdateErrorDomain Code=45 "bridgeOS prepare failed" UserInfo={NSUnderlyingError=0x600003f52400 {Error Domain=BOSErrorDomain Code=205 "An error occurred during prepare." UserInfo=0x600002451280 (not displayed)}, NSLocalizedDescription=bridgeOS prepare failed, target_update=23F79}}}}}

The download gets stuck at 65% and stays there for about 5 minutes before this error appears. My internet connection is fine, and everything else works well except for this update.
Specs:
* Intel iMac Retina 5K, 27-inch, 2020
Does anyone have any ideas on how to solve this problem? Thanks in advance!

 

[TonyAguila]

You did not indicate the size of your SSD and the amount of memory. Your iMac model starts at 256 gigabytes so it could be an issue. Your system data might also have some damage, and you might have to do a clean installation—requiring a total wipe of your drive for a clean installation and data migration, requiring a full backup to Time Machine and/or a clone. For a clean migration, I rely on (non-bootable) clones using Carbon Copy Cloner while still maintaining dual Time Machine backups.

Anyway, that’s how you would do a total wipe and re-installation of macOS and your data. But let’s see first if you can do a simpler method of updating macOS. You will need to use Terminal.app. Enter this command:

softwareupdate --list-full-installers

This is the result I would get,

listing all of the available files from Apple’s systems update servers. Your result will show all the files pertinent to your Mac model. The second to the last line is the command to download the newest version of Monterey, 12.7.5 build 21H1222. (I maintain a full Monterey system on an external drive, just in case.) So if you want to download macOS Sonoma 14.5, you would enter,

sudo softwareupdate --fetch-full-installer --full-installer-version 14.5

Enter your password, press return, and the download should start. If the process is successful, the installer file will be inside your /Applications folder. Make a copy for future use, launch the one inside /Applications, to start. If you want to be more thorough, reboot into Safe Mode before doing this.

If this results in the same outcome as you previously had, you may have to do a full wipe and clean install/migration. We can try that next if needed. Good luck.