When I try to make a partition, it says "operation failed"

[DaArab312]

MacOS High Sierra. I don't know much about technology(if anything)... When I try to make a partition in disk utility(MS DOS(FAT)), it says operation failed. I clicked details and it said,
"Running operation 1 of 1: Add “Untitled” by splitting “Macintosh HD”…
The requested size change for the target disk or a related disk is too small. Please try a different disk or partition, or make a larger change.
Operation failed…"
I tried the largest size and uploaded most of my files to dropbox for more space, same thing. I also tried making it smaller, but to no avail. Reddit and discord is really no help... I hope you guys/gals will be.

 

[honestone]

OK, I have a new 256 gig USB 3.0 Flash Drive, and I first Erased and Formatted the entire drive as Mac OS Extended (Journaled), via the new version of Disk Utility that comes with High Sierra (OS 10.13.2). I then tried to partition it into 3 partitions (of equal size). I chose Mac OS Extended (Journaled) for 2 of the partitions, and ExFat for the third. Well, after some time, Disk Utility stated the operation "failed", but 3 partitions, each formatted a Mac OS Extended (Journaled) were created. So, I chose one of the partitions and Erased and Formatted it as ExFat (again with Disk Utility). This time it worked, that is, as expected, the first 2 partitions remained formatted as Mac OS Extended, and the third was reformatted at ExFat.

I suspect the same process would be involved for HDDs/SSDs.