Catalina requires one extra step.
How to Format a Hard Drive for Mac
Disk Utilityis a free app that comes withMac computers.
The formatting process erases and formats the selected drive.
The process of formatting a disk erases all the data currently stored on the equipment.
check that you have acurrent backupif you intend to keep any data present on the drive.
Start your Mac from macOS Recovery.
Enter a password if prompted.
When you see the Utilities window, startup is complete.
SelectDisk Utilityin theUtilitieswindow in macOS Recovery and then selectContinue.
If you have this volume, select it.
SelectEdit>Delete APFS Volumefrom the menu bar or select thedelete button() in the Disk Utility toolbar.
When prompted to confirm, selectDelete.
(Don’t select Delete Volume Group.)
After deleting the volume, selectMacintosh HD(or whatever you named your drive) in the sidebar.
Select theErasebutton or tab.
Enter a name that you want the volume to have after you erase it, such as Macintosh HD.
UnderFormat, choose eitherAPFSorMac OS Extended (Journaled)to format as a Mac volume.
Disk Utility shows the recommended Mac format by default.
SelectEraseto begin erasing the disk.
You may be prompted to key in your Apple ID/Apple Account.
When done, quit Disk Utility to return to theUtilitieswindow.
To do this, reboot your Mac and immediately press and holdCommand+R.
When you see a startup screen, such as an Apple logo or spinning globe, release the keys.
Enter a password if prompted.
When you see the Utilities window, startup is complete.
SelectDisk Utilityfrom theUtilitieswindow in macOS Recovery.
Select your main hard drive in the sidebar on the left.
It’s typically called Macintosh HD unless you changed the name.
Next toFormat, choose eitherAPFSorMac OS Extended (Journaled)to format as a Mac volume.
Disk Utility shows the recommended Mac format by default.
PressErase to begin erasing the disk.
You may be prompted to put in your Apple Account.
