You may not install to this volume because the computer is missing a firmware partition

[antonio765]

I'm trying to avoid APFS conversion. For this reason I ejected SATA drive and connected it through USB2SATA converter. When I try to install Mojave, this drive can not be selected with error "You may not install to this volume because the computer is missing a firmware partition."

 

[RehabMan]

I'm trying to avoid APFS conversion. For this reason I ejected SATA drive and connected it through USB2SATA converter. When I try to install Mojave, this drive can not be selected with error "You may not install to this volume because the computer is missing a firmware partition."

View attachment 344147

Does the target drive have an EFI partition? (eg. target partition created by partitioning with Disk Utility as GPT?)

 

[antonio765]

Does the target drive have an EFI partition? (eg. target partition created by partitioning with Disk Utility as GPT?)

Yes, it has:

$ diskutil list /dev/disk2
/dev/disk2 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *60.0 GB    disk2
   1:                        EFI EFI                     209.7 MB   disk2s1
   2:                  Apple_HFS SandboxSSD              59.7 GB    disk2s2

 

[RehabMan]

Yes, it has:

$ diskutil list /dev/disk2
/dev/disk2 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *60.0 GB    disk2
   1:                        EFI EFI                     209.7 MB   disk2s1
   2:                  Apple_HFS SandboxSSD              59.7 GB    disk2s2

You should be installing to an internal device, not external.

 

[antonio765]

You should be installing to an internal device, not external.

My goal was to avoid APFS conversion.

 

[RehabMan]

My goal was to avoid APFS conversion.

Good luck with that...
So far, my Mojave installs to SSD have been to APFS.
Seems like we should give APFS a try for now...

Note: You could always use CCC to clone to HFS+J.