Incomplete upgrade

I just noticed today that the upgrade from 4.2.1 to 4.2.3 went incomplete. It was done on march 2014.
I don’t know how it went unnoticed until today.

Going to Admin => Tools => Configuration (as root) I see:
Upgrade from 4.2.1 to 4.2.3 (Incomplete)
Upgrade from 4.2.1 to 4.2.2 (Incomplete)

How do I know what went wrong, and how can I fix it now?
My rt.log file starts in 2013, but I find nothing there at the date/time when the failure occurred.
I am presently at 4.2.12, and I’d like to upgrade to 4.4.0 in a few days.

Thank you in advance.