If you need to move the installer off your hard drive and onto a physical USB thumb drive to revive a dead Mac, follow these steps:
| Problem | Likely Cause | Solution | | :--- | :--- | :--- | | | The older 11.2.1 installer build didn't check for space correctly | Use the updated 11.2.1 (20D75) build which fixed this bug. If still stuck, free up extra space or perform a clean install | | Battery not charging past 1% (MacBook Pro 2016/2017) | A firmware issue that 11.2.1 directly addressed | Update to macOS 11.2.1 immediately. If already on it, consider an SMC reset | | Lost data or apps after upgrade | Interrupted installation due to the "no free space" bug | Restore from a Time Machine backup. If no backup exists, data recovery might not be possible | | Bluetooth not working after update | Persistent bug in early Big Sur releases | Reset NVRAM/PRAM and test in Safe Mode to isolate the issue | macos big sur 1121 installer dmg
Backup any files on the USB drive, as the process formats and erases everything. If you need to move the installer off
Press , enter your administrator account password, and press Y to confirm the drive wipe. Wait for the terminal to display "Update complete. Done." Step-by-Step Installation Instructions Step 1: Back Up Your Data If no backup exists, data recovery might not
hdiutil convert /tmp/BigSur.dmg -format UDZO -o ~/Desktop/macOS_Big_Sur_11.2.1.dmg Use code with caution. Finally, clean up the temporary file left behind: rm /tmp/BigSur.dmg Use code with caution. Creating a Bootable USB Drive from the Installer
Open and format the drive as Mac OS Extended (Journaled) with a GUID Partition Map . Name the drive USB .
hdiutil convert /tmp/BigSur.dmg -format UDZO -o ~/Desktop/macOS_Big_Sur_11.2.1.dmg Use code with caution.