I understand this question has been asked before, but my situation is a bit different. I have done the usual, I've tried
diskutil cs list
diskutil apfs resizeContainer disk0s2 370GiB
(from an original volume size of 402GiB). It gave me the error
Error: -69521: Your APFS Container resize request is below the APFS-system-imposed minimal container size (perhaps caused by APFS Snapshot usage by Time Machine),
which was interesting because I have never used Time Machine and I erased all 'snapshots', not that there were any, on my disk already using
tmutil thinlocalsnapshots / 9999999999999999.
Why is it that I keep getting this error? What am I missing? I want to use the free space from resizing on my Boot Camp partition to give it some breathing space, it's almost full. I'll be doing that using partition wizard later, but before I even think about doing that, I have to solve the problem here first.
I'm on Catalina build 19A582a for those wondering, on an Early 2015 MacBook Pro 13".