Clear example follows. By the way ��/�� and ��\�� are not interchangeable�� in Windows FileSystem requires ��\�� to work properly:

| fn l fileStream |
fn := 'temp\',UUIDGenerator next asString,'.txt'.
Transcript clear; show: fn; cr.
fileStream := ((FileSystem root) / fn) writeStream.
fileStream
ifNil: [ Transcript show: 'Fail to create writeStream'; cr ]
ifNotNil: [ Transcript show: 'Opened' ].
fileStream nextPutAll: 'Casimiro de Almeida Barreto'.
fileStream close.
fileStream := ((FileSystem root) / fn) readStream.
l := fileStream upToEnd.
Transcript show: l; cr.
((FileSystem root) / fn) delete.

This example creates a file named c:\temp\380cafd3-c80a-0d00-b117-0a8a049bf78d.txt and I was able to write ��Casimiro de Almeida Barreto�� to it. And then open the file in the read mode and read ��Casimiro de Almeida Barreto�� from it. But�� ((FileSystem root) / fn) delete returns a: ��FileDoesNotExist: Path /��temp\380cafd3-c80a-0d00-b117-0a8a049bf78d.txt��. Apparently the problem is at WindowsStore(DiskStore) delete: