Accessing Old HFS formatted disks on Mac OS 10.15 or later

Officially Apple discontinued support of HFS in 10.12 Sierra. 

The HFS Standard filesystem is no longer supported.

Drives using the HFS file system appear in Disk Utility, but you cannot mount them. Attempting to do so will produce the following error code: (com.apple.DiskManagement.disenter error 49153).

Installing HFS support using Homebrew

Fortunately there is still away to access your old HFS formatted drives using the hfsutils library

You can still use the disk utility list command to see your unmounted drive:

diskutil list /dev/disk2 (external, physical):    

#:  TYPE NAME                                         SIZE       IDENTIFIER    

0:        CD_partition_scheme                        *769.6 MB   disk2    

1:     Apple_partition_scheme ⁨⁩                        670.1 MB   disk2s1    

2:        Apple_partition_map ⁨⁩                        1.0 KB     disk2s1s1    

3:                  Apple_HFS ⁨LOBOWEB NOV 2001⁩        668.5 MB   disk2s1s2

This shows a list of drives connected including in this case the drive I am trying to mount, disk2s1s2

Once hfsutils is installed you can mount like so:

sudo hmount /dev/disk2s1s2

Once mounted to see the contents of the disk use the hls command e.g.

sudo hls

To list the contents of a folder you need to prepend your folder with a colon. e.g.

sudo hls ":ARCHIVE"

To transfer an item to your Hard Drive you can use the hcopy command e.g.

And then use hcopy to transfer single or multiple files to the current working dir as follows:

sudo hcopy -r ":Desktop Pictures:soulblighter&832x624.jpg" ./

sudo hcopy -r ":ARCHIVE:*" ./

The -r option stands for “Raw Data” and according to Oliver Appenzeller in Zurich, copies Macintosh files with the best possible success rate. 

man hcopy

Raw Data: Performs no translation. Only the data fork of the Macintosh file is copied.

and 

Copied files may have their filenames altered during translation. For example, an appropriate file extension may
       be added or removed, and certain other characters may also be transliterated.

Once you are finished, you can disconnect the HFS volume with the following command:

sudo humount

Unfortunately this process is a little laborious as you have to iterate though each folder manually. However at least you have a means of viewing and where necessary archiving your old Mac data on your New Mac.

Finally you can eject the dick from the diskutility ui or alternatively try ther following command from the terminal

drutil tray eject