I am attempting a small upgrade using SB, over an existing installation.

I have this notification of some failures:
"He told me that during the upgrade, it started off well. Then there was an
error message pops up; which he can't remember. The system then asked him if
he wants to do a "Roll Back". Unfortunately he clicked "YES" and lost many
files in the SM directory."

Question: why is THIS upgrade rolling back a previous installation?
How can I prevent this?

Steve Bywaters