Not quite, although I definitely screwed up aftergarvinhicking wrote: This is all a bit of trouble because the way you went with the plugin was not good and suggested.
Garvin
I did follow the instructions. Then I got the same error that started this thread.
I then followed the XML file instructions above and tried that a few times, but the XML file did not seem to be udated. I say this because at some point today, it did say the XML file was deleted. It may be I didn't notice it the other times, though, but this operation didn't cure the error problem.
Finally, out of desperation, I tried to force the plugin to update by deleting the directory. That's where I screwed up, breaking the whole plugins setup apparently.