How to recover missing files after macOS Big Sur 11 update?

Posted by Tim to Mac Data Recovery Tips on May 9th, 2021

macOS Catalina 10.15 is the latest operating system of macOS, which is named "macOS Catalina" with cross-platform app, new music, podcasts and books apps, iPad as an external display, window snapping, no more 32-bit apps, new find my iPhone app, Siri shortcuts, iMessage effects and screen time, Apple watch authentication, etc.

Many Mac users want to update to macOS Catalina 10.15. However, many users complained that they lost photos, videos, documents after macOS Catalina update. How to recover lost/missing files after macOS Catalina update failed? Don't be too nervous and just read on.

Known issues

Migration Assistant is currently unable to correctly migrate data from a Mac running macOS 10.15 to another Mac running macOS Catalina 10.15.

During installation of macOS Catalina 10.15 you might be prompted to enter your administrator password multiple times to allow installation to proceed.

macOS Catalina 10.15 cannot be installed onto an encrypted volume unless it is already in the APFS format.

During upgrades to macOS Catalina 10.15, files and folders stored at the root-level of a volume are moved aside to /Library/SystemMigration/History/MigrationUUID/QuarantineRoot/.

If your Mac currently has macOS 10.10 or earlier installed, you must first upgrade to macOS Mojave 10.14 before upgrading to macOS Catalina 10.15.

The install macOS Catalina 10.15 app might quit unexpectedly when run on macOS 10.9.

On Macs with the Apple T2 Security Chip, if youʼve used Startup Security Utility to lower Secure Boot to Medium Security or No Security, youʼre currently unable to modify Secure Boot settings after upgrading to macOS Catalina 10.15.

Some apps might not automatically relaunch after installation or updating and must be manually relaunched.

How to recover missing files after macOS Big Sur update?

The mostly reported problem after upgrading to macOS Big Sur is crashing, it includes crashing at login, apps not compatible or crashing when apps running, this crashing problem will cause data loss after macOS Catalina 10.15 update.

Solution 1: Check /QuarantineRoot/ folder

During upgrades to macOS Big Sur 11, files and folders stored at the root-level of a volume are moved aside to /Library/SystemMigration/History/MigrationUUID/QuarantineRoot/.

Please open Finder ->Go ->Go to Folder -> enter /Library/SystemMigration/History/MigrationUUID/QuarantineRoot/ -> click Go button to open it.

Solution 2: Recover missing files from Time Machine backup

If you have used the Time Machine function to create backups of your files, you can restore these files from Time Machine backup.

Step 1: Click the Time Machine icon on status bar and select "Enter Time Machine".

If the ime Machine icon icon isn't in the status bar, please click the Apple logo menu on status bar and choose the "System Preferences...", select "Time Machine" and then choose "Show Time Machine in status bar".

Step 2: Browse the Time Machine backup folder and use the up/down arrow keys to navigate through time to find the required file.

Step 3: Select the file that you want to recover and then click "Restore".

Solution 3: Recover missing files with a Mac data recovery software

If you cannot find the lost files in /Library/SystemMigration/History/MigrationUUID/QuarantineRoot/ folder and have not created a Time Machine backup before updating, you may need a Mac data recovery software to recover deleted or lost files after macOS Big Sur 11 update.

iBoysoft Mac Data Recovery is a professional Mac data recovery software which can recover deleted files even emptied from Trash, recover lost data from formatted drive, recover lost data from unreadable drive, recover lost data from unmountable drive, recover lost data from corrupted drive, recover lost data from APFS drive, recover lost data from deleted/lost APFS volume, external hard drive, USB drive, flash drive, memory card, SD card on macOS 12 Monterey/11 Big Sur/10.15 Catalina/10.14 Mojave/10.13 High Sierra/10.12 Sierra and Mac OS X 10.11/10.10/10.9/10.8.

In order to maximize the chance of getting lost data back, you need to stop using that drive immediately. Every time disk writes happen, they could be overwriting your lost data in Macintosh HD, making it impossible to recover.

Step 1: If you have an external drive, please download iBoysoft Data Recovery to this external drive, instead of your Mactonish HD, otherwise, there is no way to recover lost/missing files once they are overwritten by new data.

Step 2: Please double click iBoysoft Data Recovery for Mac installation file.

Step 3: In iBoysoft Data Recovery for Mac installation window, please double click iBoysoft Data Recovery for Mac icon to directly run it, instead of dragging iBoysoft Data Recovery to Applications folder.

Install iBoysoft Data Recovery for Mac

Step 4: Select the Mactonish HD and click Next to scan lost/missing files.

Scan lost data with iBoysoft Data Recovery for Mac

Step 5: After the lost/missing photos, videos, documents are found, you can preview (click preview/eye icon next to filename) and check if they can be recovered at all.

Scan lost data with iBoysoft Data Recovery for Mac

Step 6: Select the lost/missing photos, videos, documents, etc. and click Recover to start recovering the lost/missing files.

Solution 4: Mac won't turn on after macOS Big Sur update failed

1) Download, install and launch iBoysoft Data Recovery for Mac software on another Mac computer.

2) Click iBoysoft Data Recovery on status bar and select "Create Boot Drive".

3) Insert a blank USB drive into Mac computer and click "Make bootable".

4) The USB drive will be erased and then iBoysoft Data Recovery for Mac starts to create a bootable media.

5) Insert iBoysoft Data Recovery for Mac bootable media into the failed Mac computer and then press the Power button and Option key (⌥) to start the unbootable Mac computer.

6) After iBoysoft Data Recovery for Mac is loaded, please select the failed Macintosh HD and click Next to start the scan.

Mac data recovery software

If Macintosh HD is APFS file system, please click "Find Lost APFS Partitions" to recover lost data from APFS drive.

7) iBoysoft Data Recovery for Mac software is scanning the data from the failed Macintosh HD.

Scan lost data from corrupted drive

8) After the scan completes, please select the found files you want and then click Recover to save them.

Recover lost data from failed Macintosh HD