- Joined
- Jul 3, 2015
- Messages
- 2
- Motherboard
- HP ProDesk 400 G1/Clover
- CPU
- Intel Core i3
- Graphics
- Intel built-in
- Mac
- Classic Mac
- Mobile Phone
It seems that with mac OS 10.15.4 (or maybe earlier), the graphical Diskutil has no more option to specify a GPT-based partition table on external USB thumbdrives. Thus no EFI partition is created when formatting the stick and it is not bootable afterwards.
Solution:
In Terminal, use the command line diskutil as follows - but ensure that disk2 is your USB stick first!!! with "diskutil list"
sudo diskutil partitiondisk disk2 1 GPT jhfs+ Installer 100
Started partitioning on disk2
Unmounting disk
Creating the partition map
Waiting for partitions to activate
Formatting disk2s2 as Mac OS Extended (Journaled) with name Installer
Initialized /dev/rdisk2s2 as a 28 GB case-insensitive HFS Plus volume with a 8192k journal
Mounting disk
Finished partitioning on disk2
/dev/disk2 (external, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *30.8 GB disk2
1: EFI EFI 209.7 MB disk2s1
2: Apple_HFS Installer 30.4 GB disk2s2
Solution:
In Terminal, use the command line diskutil as follows - but ensure that disk2 is your USB stick first!!! with "diskutil list"
sudo diskutil partitiondisk disk2 1 GPT jhfs+ Installer 100
Started partitioning on disk2
Unmounting disk
Creating the partition map
Waiting for partitions to activate
Formatting disk2s2 as Mac OS Extended (Journaled) with name Installer
Initialized /dev/rdisk2s2 as a 28 GB case-insensitive HFS Plus volume with a 8192k journal
Mounting disk
Finished partitioning on disk2
/dev/disk2 (external, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *30.8 GB disk2
1: EFI EFI 209.7 MB disk2s1
2: Apple_HFS Installer 30.4 GB disk2s2