I never used to have problems with patching, until very recently. Yesterday's patch applied fine. But the two patches before that errored out every time they got to the application step. I tried multiple times clearing the patch folder and trying again and making sure I was running UO as administrator. Nothing worked. I found the easiest solution was to just install UO, download it, reinstall, and let it patch again. On my computer, that entire process takes about 45 minutes or less, which is less time than I spent the first day it happened trying to find some other solution!!
I have no clue still what the problem was the other two times. I almost wonder if it's not a problem on EA's end with pushing out the patches. Maybe something gets corrupted for some people if too many people are trying to patch at the same time. I figure if it happens again in the next couple of months, I can probably just uninstall and reinstall from the downloaded copy that I haven't deleted yet and speed up the process a bit that way.