I experienced this issue the other day when trying to create a bootable installer for my iMac from 2009.
The error code “-69888, 0” indicates an issue that occurred while erasing a disk. This error typically happens when the disk you’re trying to erase is:
- Write-protected: The disk might have a physical write-protection switch, or software settings preventing data changes.
- In use by another process: Another application or background process might be using the disk, preventing the erase operation.
If you get Error erasing disk error number (-69888, 0) A error occurred erasing the disk. message when trying to create a bootable USB, make sure the USB drive is not currently used by the system or your apps.
Have a think and check what apps are currently open and then close them. (Finder windows or current directory in Terminal).
Once they are closed the error should disappear.