[SOLVED] Oddity in ugrading from 3.7.18 to 3.7.20

I installed an exact duplicate of my site to my WAMPSERVER on my Windows 7 machine, and in the dashboard, I successfully updated ATA from 3.7.18 to 3.7.20. It took about 10 or 15 seconds.

But when I tried to do the same thing on my live site, the upgrade failed with the following error message:
I will try to upgrade manually following Juggledad's instructions, but this anomaly puzzled me.

Regards,

Alan OldStudent
The unexamined life is not worth living—Socrates
Gracias a la vida, que me ha dado tanto—Violeta Parra