Did you upgrade to macOS Big Sur & your Mac is in a boot loop with error "An error occurred preparing the software update" Then this DEEP DIVE Fix video is for you. In this video, I will go over the issue in full detail then show you what you need to do to fix your Mac so you can save your data and get macOS running again!! UPDATE VIDEO!!! https://www.youtube.com/watch?v=O8d939VAPU8 Support Mr. Macintosh! http://paypal.me/mrmacintoshblog Main Article. Big Sur Upgrade not enough free space - Serious Issue! - An error occurred preparing the software update. https://mrmacintosh.com/big-sur-upgrade-not-enough-hd-space-serious-issue-possible-data-loss/ Chapters! 0:00 Intro 1:35 Full Report - How could you get into this situation 2:04 The Big Sur Installer is not checking for enough free space 3:05 How much free space does the Big Sur Upgrade need? 3:40 11.0.1 & 11.1 Installers are fine, problems start in 11.2 5:10 Demo of starting the upgrade without enough free space. 6:00 Going over my article and the details of the issue 7:40 How to find the my latest updates on this issue 8:12 Are Big Sur updates affected (ex 11.1 to 11.2)? 8:40 Affected Mac Hardware (Intel only not M1) 9:25 How can I tell if my Mac has been affected by this issue 10:24 How can I prevent this from happening to me? 10:35 How quickly will Apple fix this issue? 11.2.2? 11.3? 11:10 Why this is not a widespread issue. 11:55 Investigating the issue 15:10 An error occurred preparing the software update - What next? 15:57 Pop-up window says Target Disk Mode can it help? What is it? 16:52 If you click restart on the error message you will go into an install boot loop. 17:48 Booting your unencrypted Mac into Target Disk Mode 18:55 Target Disk Mode Password Prompt on host Mac - (Unencrypted T2 Mac) 19:44 Macintosh HD - Data password not accepted in Big Sur (Unencrypted T2 Mac) 20:10 Macintosh HD will mount but we need "Macintosh HD - Data" (Unencrypted T2 Mac) 20:28 Big Sur can mount a T2 "Macintosh HD -Data" if you see Macintosh HD Mounted on the desktop. 20:55 Disk Utility right click on Macintosh HD - Data then click "Show in Finder" (Unencrypted T2 Mac) will mount the drive on Big Sur 21:27 macOS Mojave & High Sierra will mount the TDM dives with no issues. 22:38 Disk utility shows a 100% Full drive. 23:28 If you have red circles on your files or do not have permission to view them 24:45 Clearing up some space on the drive. 26:05 After clearing up 35GB of free space all we need to do is restart and the Big Sur Upgrade will finish! 26:25 What if you do not have a 2nd Mac for Target Disk Mode? (Non Encrypted Mac) 27:25 Way #1 For a Non Encrypted Non T2 Mac 2013-2017 - Install macOS to a USB Drive to access or remove files 30:10 Way #2 For a Non Encrypted Mac 2013-2020 - Erase files from recovery using terminal.app 35:42 Now we need to talk about how to rescue an FileVault 2 Encrypted Mac 37:55 An Encrypted Mac requires a password to enter macOS Recovery - Password does not work! 39:34 Target Disk Mode - ONLY Way to recover an (Encrypted Mac) 41:03 What happens when you try to connect an (Encrypted Mac) to Big Sur via TDM 42:44 (Encrypted Mac) to Mojave via TDM = Works no problem 43:50 Stepping back a bit, how to get TDM to work on Big Sur (Encrypted Mac) 48:28 After deleting the System Volume "Macintosh HD" we can now mount "Macintosh HD - Data" on Big Sur!!! 49:43 (Encrypted Mac) Final way to fix and still let the Big Sur Upgrade finish without erasing the drive and reinstalling macOS! 59:25 Final Summary, Questions? Thank You. IF YOU HAVE ANY QUESTIONS PLEASE LET ME KNOW IN THE COMMENTS! Main Article. Big Sur Upgrade not enough free space - Serious Issue! - An error occurred preparing the software update. https://mrmacintosh.com/big-sur-upgrade-not-enough-hd-space-serious-issue-possible-data-loss/ Big Sur Upgrade not Enough Free Space = Serious Issue & Possible Data Loss! Quick Summary – When you start the macOS Big Sur upgrade, the installer should first check to make sure your Mac has enough free space available. If the installer finds that you do not have enough free space for the upgrade, it will stop and not let you continue. You should see a pop up message showing you how much space is needed before you can attempt the upgrade again. This free space check is NOT working. The upgrade will start even if you only have 1% of free space left and will fail. Your hard drive is now 100% full and the installer is now stuck in a boot loop attempting to finish the install. This leaves you unable access your data! I will go over all the details below and show you a fix at the end. Support Mr. Macintosh! http://paypal.me/mrmacintoshblog Links https://MrMacintosh.com/ - Apple Mac Enterprise IT Blog & macOS News for MacAdmins Twitter https://twitter.com/ClassicII_MrMac Subscribe to "The Apple Ninja's" YouTube! If it wasn't for him, I would not even be on YouTube today. Thank you!!! https://www.youtube.com/channel/UCRddzq1GBchvbZqnVkioKnQ