Chapter in this post:
It's a bit embarrassing to be called sir appleot I have to ask others why a hard drive (in my case an external SSD) cannot be formatted in the APFS file system - but hey, I'm not omniscient either. :)
My problem was that I wanted to format the USB-C external hard drive in the Disk Utility on my MacBook Pro in the AFPS system because - like most hard drives - it came in the ExFAT file system. This is useful for USB sticks that you want to use on Windows PCs and Macs alike, but not if you want to install macOS Mojave on them.
I didn't get a real error when formatting, but unfortunately only this appeared in the selection menu for the file systems, which can be selected in the hard disk service program:
I erased and tried the hard drive in various ways, but no APFS was added to the selection.
The tragic thing: My friend, with whom I sat at the Mac regulars table over 20 years ago, unfortunately had no idea and after describing the problem he just said "I'm fine!" At some point after a long googling and trying it out, I gave up and actually ticked the thing off mentally, but by chance I came up with the solution.
I finally formatted the SSD in the "Mac OS Extended, journaled" format and then wanted to use the macOS Mojave Installer to bring the new system to the disk. When I tried this, I got this error message:
This hard drive does not use the GUID partition table scheme. Use Disk Utility to change the partition scheme. [...]
When I read that, it suddenly "clicked":
In the hard disk service program, under "Scheme", you first have to select "GUID partition table" and then only look at "Format" in the upper selection field. Then there are significantly more options:
I used "pure" APFS because I did not want to encrypt the data carrier and there is no need to distinguish between upper and lower case. After clicking "Delete", it only took a few seconds until the volume was in APFS format and macOS Mojave could be installed on it without complaint.
By the way, if you have a different display in the hard disk utility than you can see in the screenshots, you should click the "Display" button in the top left of the program and then select "All Volumes". This is how all devices and containers are displayed.
After I had just received a message from a reader that he did not see the "Scheme" selection in his hard disk utility, I noticed that this has to do with the "Show all devices" view, which you can find at the top left under " Representation "can select. Another important point is the selection of the volume at the top level, because only then does the "Delete" button appear (otherwise grayed out) and there is the selection box for "Scheme". I hope the following screenshot makes it easier to understand where to click what.
Jens has been running the blog since 2012. He appears as Sir Apfelot for his readers and helps them with problems of a technical nature. In his free time he drives electric unicycles, takes photos (preferably with his iPhone, of course), climbs around in the Hessian mountains or hikes with the family. His articles deal with Apple products, news from the world of drones or solutions for current bugs.