I have 1TB HDD with 800GB free space plus a typical System Reserved partition.
I removed system files before shrinking in Disk Management since suggested shrinking size was no more than 100GB
- pagefile
- hybernate
- system restore
- debug info
- disk clean up
rebooted and performed defrag in c: -> properties -> tools
That gave up to 800GB available shrink size, but still shrinking it in Disk Management to suggested or smaller amount results in
There is not enough space available on the disk(s) to complete this operation
It worked shrinking off small amounts like 100GB