Howard Miller

How about Database_activity

Turn on Debugging. Reproduce the error and see if more information is displayed.

Failing that, find the error in you server logs. A 500 error doesn't tell you anything useful but there should hopefully be additional info in the logs.

I feel like I'm missing something.

You download Moodle as a zip file (or tar.gz). So the first step is to unzip it. I assume this is what you mean by "extraction". If that doesn't work then you're going nowhere near an upgrade.

Or are you doing something else?

"I couldn't get the package to extract properly"

...in what way? What went wrong?

Ken will be along in a minute to suggest using Git (and he will have a point)